Apparatus and method for cleaning or de-icing vehicle elements

ABSTRACT

A liquid heating assembly ( 102 ) including a heat-conductive displaceable element ( 250 ) and a liquid heating enclosure ( 210, 212 ) defining a liquid heating volume including a primary liquid ( 258 ) heating volume portion and a secondary liquid heating volume portion ( 254 ), separated by the heat-conductive displaceable element ( 250 ), the primary liquid heating volume portion including a heat exchanger for directly heating liquid in the primary liquid heating volume portion and for indirectly heating liquid in the secondary liquid heating volume portion via the heat-conductive displacement element ( 250 ).

REFERENCE TO CO-PENDING APPLICATIONS

Applicant hereby claims priority of U.S. Provisional Patent ApplicationSer. No. 60/451,600 filed on Mar. 3, 2003, entitled “System And MethodFor Swift Cleaning Or De-Icing Windshields” and U.S. Provisional PatentApplication Ser. No. 60/420,001, filed Oct. 21, 2002, entitled “SystemAnd Method For Swift Cleaning Or Deicing Windshields”

FIELD OF THE INVENTION

The present invention relates generally to apparatus and method forcleaning or de-icing vehicle elements.

BACKGROUND OF THE INVENTION

The following publications are believed to represent the current stateof the art:

U.S. Pat. Nos.: 6,164,564; 6,199,587; 5,509,606; 5,118,040; 4,090,668;5,012,977; 5,354,965; 3,979,068; 4,090,668; 4,106,508; 5,012,977;5,118,040; 5,254,083; 5,354,965; 5,383,247; 5,509,606; 5,927,608;5,947,348 and 5,988,529.

Published PCT Applications: WO 02/092237, WO 00/27540 and WO 98/58826.

SUMMARY OF THE INVENTION

The present invention seeks to provide improved apparatus and method forcleaning or de-icing vehicle elements.

There is thus provided in accordance with a preferred embodiment of thepresent invention a liquid heating assembly including a heat-conductivedisplaceable element and a liquid heating enclosure defining a liquidheating volume including a primary liquid heating volume portion and asecondary liquid heating volume portion, separated by theheat-conductive displaceable element, the primary liquid heating volumeportion including a heat exchanger for directly heating liquid in theprimary liquid heating volume portion and for indirectly heating liquidin the secondary liquid heating volume portion via the heat-conductivedisplacement element.

In accordance with another preferred embodiment of the present inventionthe heat-conductive displaceable element includes a resilient, flexibleelement. Additionally or alternatively, the heat-conductive displaceableelement forms at least a wall both of the primary liquid heating volumeportion and of the secondary liquid heating volume portion.

In accordance with yet another preferred embodiment of the presentinvention at least the liquid heating enclosure defines a primary liquidflow pathway in the primary liquid heating volume portion and asecondary liquid flow pathway in the secondary liquid heating volumeportion, the secondary liquid flow pathway supplying liquid to theprimary liquid flow pathway.

Preferably, the primary liquid heating volume portion is formed of arelatively rigid, highly heat conductive material. Additionally, thesecondary liquid heating volume portion is formed of a material which isless rigid and less heat conductive than the material forming theprimary liquid heating volume portion.

In accordance with another preferred embodiment of the present inventionat least the primary liquid flow pathway is defined by the liquidheating enclosure and by the heat-conductive displacement element. Inaccordance with yet another preferred embodiment of the presentinvention at least the liquid heating enclosure defines an at leastpartially turbulent flow primary liquid flow pathway in the primaryliquid heating volume portion and an at least partially turbulent flowsecondary liquid flow pathway in the secondary liquid heating volumeportion, the at least partially turbulent flow secondary liquid flowpathway supplying liquid to the at least partially turbulent flowprimary liquid flow pathway.

In accordance with still another preferred embodiment of the presentinvention the primary liquid heating volume portion is formed at leastpartially of a metal material, which is relatively highly heatconductive and the secondary liquid heating volume portion is formed atleast partially of a plastic material, which is relatively heatinsulative, separated by the heat-conductive displaceable element,formed of a material which is less heat conductive than the metalmaterial. Additionally, the heat-conductive displaceable element isformed of a material which is more heat conductive than the plasticmaterial.

In accordance with another preferred embodiment of the present inventionthe heat-conductive displaceable element is apertured to permit liquidcommunication from the secondary liquid heating volume portion to theprimary liquid heating volume portion.

In accordance with another preferred embodiment of the present inventionthe secondary liquid heating volume portion includes at least onedisplaceable outer wall portion providing freeze protection by virtue ofits displaceability. Additionally, the heat-conductive displaceableelement is operative to be displaced into the secondary liquid heatingvolume portion upon freezing of liquid inside the primary liquid heatingvolume portion.

In accordance with yet another preferred embodiment of the presentinvention the heat-conductive displaceable element is an interveningliquid impermeable diaphragm.

In accordance with still another preferred embodiment of the presentinvention the primary liquid heating volume portion is a first conduitelement and the secondary liquid heating volume portion is a secondconduit element. Additionally, the heat exchanger is defined by thefirst conduit element and the second conduit element.

There is also provided in accordance with another preferred embodimentof the present invention vehicle including a vehicle chassis including adrive train, a vehicle body including at least one vehicle surface whichrequires washing, a vehicle washing liquid reservoir, a vehicle washingliquid discharge assembly, a vehicle surface washer assembly operativeto employ the vehicle washing liquid discharge assembly and a washingliquid from the vehicle washing liquid reservoir for washing the atleast one vehicle surface which requires washing and a liquid heatingassembly operative to employ the vehicle washing liquid dischargeassembly and the washing liquid from the vehicle washing liquidreservoir for providing a spray of heated liquid onto the at least onevehicle surface which requires washing, the liquid heating assemblyincluding a heat-conductive displaceable element and a liquid heatingenclosure defining a liquid heating volume including a primary liquidheating volume portion and a secondary liquid heating volume portion,separated by the heat-conductive displaceable element, the primaryliquid heating volume portion including a heat exchanger for directlyheating liquid in the primary liquid heating volume portion and forindirectly heating liquid in the secondary liquid heating volume portionvia the heat-conductive displacement element.

There is further provided in accordance with yet another preferredembodiment of the present invention a vehicle including a vehiclechassis including a drive train, a vehicle body including at least onevehicle surface which requires washing, a vehicle washing liquidreservoir, a vehicle washing liquid discharge assembly, a vehiclesurface washer assembly operative to employ the vehicle washing liquiddischarge assembly and a washing liquid from the vehicle washing liquidreservoir for washing the at least one vehicle surface which requireswashing, a liquid heating assembly operative to employ the vehiclewashing liquid discharge assembly and the washing liquid from thevehicle washing liquid reservoir for providing a spray of heated liquidonto the at least one surface which requires washing and a normallyclosed automatically operative valve interconnecting the vehicle washingliquid reservoir to the vehicle washing liquid discharge assembly andbeing operative, when open, to bypass the liquid heating assembly.

In accordance with another preferred embodiment of the present inventionthe vehicle also includes a vehicle pump connected upstream of the atleast one vehicle washing liquid reservoir and downstream of thenormally closed automatically operative valve. Additionally oralternatively, the liquid heating assembly includes a heat-conductivedisplaceable element and a liquid heating enclosure defining a liquidheating volume including a primary liquid heating volume portion and asecondary liquid heating volume portion, separated by theheat-conductive displaceable element, the primary liquid heating volumeportion including a heat exchanger for directly heating liquid in theprimary liquid heating volume portion and for indirectly heating liquidin the secondary liquid heating volume portion via the heat-conductivedisplacement element.

Preferably, the heat-conductive displaceable element includes aresilient, flexible element. Additionally or alternatively, theheat-conductive displaceable element forms at least a wall both of theprimary liquid heating volume portion and of the secondary liquidheating volume portion.

In accordance with yet another preferred embodiment of the presentinvention at least the liquid heating enclosure defines a primary liquidflow pathway in the primary liquid heating volume portion and asecondary liquid flow pathway in the secondary liquid heating volumeportion, the secondary liquid flow pathway supplying liquid to theprimary liquid flow pathway.

In accordance with still another preferred embodiment of the presentinvention the primary liquid heating volume portion is formed of arelatively rigid, highly heat conductive material. Additionally, thesecondary liquid heating volume portion is formed of a material which isless rigid and less heat conductive than the material forming theprimary liquid heating volume portion.

In accordance with another preferred embodiment of the present inventionat least the primary liquid flow pathway is defined by the liquidheating enclosure and by the heat-conductive displacement element.Additionally or alternatively, at least the liquid heating enclosuredefines an at least partially turbulent flow primary liquid flow pathwayin the primary liquid heating volume portion and an at least partiallyturbulent flow secondary liquid flow pathway in the secondary liquidheating volume portion, the at least partially turbulent flow secondaryliquid flow pathway supplying liquid to the at least partially turbulentflow primary liquid flow pathway. Additionally or alternatively, theprimary liquid heating volume portion is formed at least partially of ametal material, which is relatively highly heat conductive and thesecondary liquid heating volume portion is formed at least partially ofa plastic material, which is relatively heat insulative, separated bythe heat-conductive displaceable element, formed of a material which isless heat conductive than the metal material. Preferably, theheat-conductive displaceable element is formed of a material which ismore heat conductive than the plastic material.

In accordance with yet another preferred embodiment of the presentinvention the heat-conductive displaceable element is apertured topermit liquid communication from the secondary liquid heating volumeportion to the primary liquid heating volume portion. Additionally oralternatively, the secondary liquid heating volume portion includes atleast one displaceable outer wall portion providing freeze protection byvirtue of its displaceability. Additionaly, the heat-conductivedisplaceable element is operative to be displaced into the secondaryliquid heating volume portion upon freezing of liquid inside the primaryliquid heating volume portion.

In accordance with still another preferred embodiment of the presentinvention the at least one vehicle surface which requires washingincludes at least one of the following surfaces: a front vehiclewindshield surface, a back vehicle windshield surface, a side vehiclewindow surface, a vehicle headlight surface, a vehicle rear lightsurface, a vehicle radar antenna surface and a vehicle exterior mirrorsurface.

In accordance with still another preferred embodiment of the presentinvention the heat-conductive displaceable element is an interveningliquid impermeable diaphragm. In accordance with yet another preferredembodiment of the present invention the primary liquid heating volumeportion is a first conduit element and the secondary liquid heatingvolume portion is a second conduit element. Additionally, the heatexchanger is defined by the first conduit element and the second conduitelement.

In accordance with another preferred embodiment of the present inventionthe normally closed automatically operative valve is a differentialpressure responsive one-way valve.

In accordance with still another preferred embodiment of the presentinvention user activation activates the spray of heated liquid onto theat least one vehicle surface which requires washing. Additionally oralternatively, automatic activation activates the spray of heated liquidonto the at least one vehicle surface which requires washing.Preferably, the automatic activation is provided by an AGC actuationsignal.

In accordance with yet another preferred embodiment of the presentinvention the liquid heating assembly is operative to employ the vehiclewashing liquid discharge assembly and the washing liquid from thevehicle washing liquid reservoir for providing a spray of liquid onto avehicle windshield surface and a vehicle radar antenna surface.

In accordance with still another preferred embodiment of the presentinvention the vehicle also includes a normally-open valveinterconnecting vehicle windshield sprayers of the vehicle windshieldsurface to the vehicle washing liquid discharge assembly and beingoperative, when open, to bypass vehicle radar antenna sprayers of thevehicle radar antenna surface. In accordance with another preferredembodiment of the present invention the vehicle also includes a flowrestrictor, restricting flow to the vehicle radar antenna sprayers toensure liquid is supplied to the vehicle windshield sprayers when thenormally-open valve is open.

There is further provided in accordance with yet another preferredembodiment of the present invention a liquid heating method includingproviding a liquid heating enclosure defining a liquid heating volumeincluding a primary liquid heating volume portion and a secondary liquidheating volume portion, separated by a heat-conductive displaceableelement and directly heating liquid in the primary liquid heating volumeportion, thereby indirectly heating liquid in the secondary liquidheating volume portion via the heat-conductive displacement element.

There is further provided in accordance with still another preferredembodiment of the present invention a vehicle operation method includingproviding a vehicle including at least one vehicle surface whichrequires washing and washing the at least one vehicle surface whichrequires washing by supplying heated liquid from a reservoir as a sprayof heated liquid onto the at least one surface which requires washingincluding causing liquid from the reservoir to be directly heated in aprimary liquid heating volume portion and to be indirectly heated in asecondary liquid heating volume portion via a heat-conductive elementseparating the primary and secondary liquid heating volume portions.

There is yet further provided in accordance with still another preferredembodiment of the present invention a vehicle operation method includingproviding a vehicle including at least one vehicle surface whichrequires washing and washing the at least one vehicle surface whichrequires washing by at least one of supplying heated liquid from aliquid reservoir via a liquid heating assembly as a spray of heatedliquid onto the at least one surface which requires washing andsupplying unheated liquid from the liquid reservoir via a normallyclosed automatically operative valve which, when open, bypasses theliquid heating assembly.

In accordance with another preferred embodiment of the present inventiona vehicle pump connects upstream of the liquid reservoir and downstreamof the normally closed automatically operative valve.

In accordance with another preferred embodiment of the present inventionthe vehicle operation method also includes providing a vehicle includingthe at least one vehicle surface which requires washing and washing theat least one vehicle surface which requires washing by supplying heatedliquid from the liquid reservoir as a spray of heated liquid onto the atleast one surface which requires washing including causing liquid fromthe liquid reservoir to be directly heated in a primary liquid heatingvolume portion and to be indirectly heated in a secondary liquid heatingvolume portion via a heat-conductive element separating the primary andsecondary liquid heating volume portions.

In accordance with another preferred embodiment of the present inventionthe primary and secondary liquid heating volume portions are defined bya liquid heating enclosure and the primary liquid heating volume portionincludes a heat exchanger for directly heating the liquid in the primaryliquid heating volume portion and for indirectly heating the liquid inthe secondary liquid heating volume portion via the heat-conductivedisplacement element.

In accordance with still another preferred embodiment of the presentinvention the heat-conductive displaceable element is resiliently andflexibly displaceable. Additionally or alternatively, theheat-conductive displaceable element separates the primary liquidheating volume portion and the secondary liquid heating volume portion.In accordance with still another preferred embodiment of the presentinvention the liquid flows into a primary liquid flow pathway in theprimary liquid heating volume portion from a secondary liquid flowpathway in the secondary liquid heating volume portion. Additionally oralternatively, at least the liquid flows in at least partially turbulentflow primary liquid flow through the primary liquid heating volumeportion following flowing in at least partially turbulent flow secondaryliquid flow through the secondary liquid heating volume portion.

In accordance with yet another preferred embodiment of the presentinvention the liquid flows via an aperture formed in the heat-conductivedisplaceable element to permit liquid communication from the secondaryliquid heating volume portion to the primary liquid heating volumeportion.

In accordance with another preferred embodiment of the present inventionat least one displaceable outer wall portion of the secondary liquidheating volume portion is displaced into the secondary liquid heatingvolume portion upon freezing of liquid inside the primary liquid heatingvolume portion.

In accordance with another preferred embodiment of the present inventionthe washing includes an initial spray cycle. Additionally, theindirectly heating liquid in the secondary liquid heating volume portionduring a relatively long time duration after initial operation of amotor of the vehicle causes the initial spray cycle to be relativelylonger than when the indirectly heating liquid in the secondary liquidheating volume portion is during a relatively short time duration afterinitial operation of the motor of the vehicle. Additionally, thesupplying heated liquid onto the at least one surface is nearlyinstantaneous when the indirectly heating liquid in the secondary liquidheating volume portion is for a relatively long time duration after theinitial operation of the motor of the vehicle.

There is also provided in accordance with another preferred embodimentof the present invention a heated liquid discharge system including amain assembly which provides liquid heating and includes electrical andliquid flow control functionalities, a liquid inflow conduit supplyingliquid from a liquid reservoir to the main assembly and a liquid outflowconduit supplying liquid to at least one sprayer located at at least onelocation on a motor vehicle, the main assembly including a liquidheating chamber communicating with the liquid inflow conduit and theliquid outflow conduit and being formed with a liquid drain aperturelocated on a side thereof which permits draining of liquid from theliquid heating chamber generally down to a level of the liquid drainaperture.

In accordance with another preferred embodiment of the present inventionthe draining takes place when a vehicle pump supplying liquid to theliquid inflow conduit is not in operation. In accordance with anotherpreferred embodiment of the present invention the at least one locationincludes at least one of the following locations: front vehiclewindshield, back vehicle windshield, side vehicle windows, surfacevehicle headlights, vehicle rear lights and vehicle exterior mirrors.

In accordance with another preferred embodiment of the present inventiona vehicle operator actuation switch is electrically coupled to the mainassembly. Additionally or alternatively, the main assembly is connectedto a vehicle computer. Alternatively or additionally, the main assemblyis connected to a vehicle ignition switch.

In accordance with still another preferred embodiment of the presentinvention the main assembly includes a principal housing portion and acover housing portion. Additionally, the principal housing portiondefines a generally circular cylindrical liquid heating chamberaccommodating volume in a major portion of which is disposed a liquidheating assembly including the liquid heating chamber.

In accordance with yet another preferred embodiment of the presentinvention the liquid heating chamber includes a generally circularcylindrical outer sleeve. Additionally, the liquid heating assemblyincludes a plurality of heating elements located within the liquidheating chamber. In accordance with another preferred embodiment of thepresent invention electrical characteristics of individual ones of theplurality of heating elements are different from each other.

In accordance with still another preferred embodiment of the presentinvention the principal housing portion defines a liquid inlet channeland a heated liquid outlet channel, both communicating with the liquidheating chamber accommodating volume and respectively communicating withthe liquid inflow conduit and the liquid outflow conduit. Additionally,the principal housing portion also defines a heated liquid temperaturesensor mounting aperture which communicates with the liquid heatingchamber accommodating volume.

In accordance with yet another preferred embodiment of the presentinvention liquid supplied to the liquid heating chamber accommodatingvolume via the liquid inlet channel enters the liquid heating chambervia at least two liquid inlet apertures formed in the liquid heatingchamber including a first aperture located near a base of the liquidheating chamber and a second aperture located at an opposite side of theliquid heating chamber from the first aperture and near a middle of aheight of the liquid heating chamber. Additionally, during operation ofthe vehicle pump supplying liquid to the liquid inflow conduit a levelof the liquid exceeds the height of the liquid heating chamber and fillsthe liquid heating chamber accommodating volume.

In accordance with another preferred embodiment of the present inventionthe liquid drain aperture is located on a side of the liquid heatingchamber just below the top thereof, which permits draining of the liquidfrom the liquid heating chamber accommodating volume generally only downto the level of the liquid drain aperture when the vehicle pump is notin operation. In accordance with still another preferred embodiment ofthe present invention the liquid from the liquid reservoir is suppliedby the vehicle pump via the liquid inlet conduit via a liquid inletpathway portion of a liquid connector assembly, which also defines aliquid outlet pathway portion.

In accordance with another preferred embodiment of the present inventionthe liquid connector assembly defines a differential pressure bypasspathway portion, which is controlled by a one-way valve and whichpermits liquid flow from the liquid inlet pathway portion to the liquidoutlet pathway portion when a pressure differential thereacross reachesa predetermined threshold, which indicates the existence of a blockagein a liquid path through the liquid heating chamber accommodatingvolume. Additionally, the liquid inlet pathway portion includes a leakyone way valve which permits supply of liquid under pressure to theliquid heating chamber accommodating volume but restricts backflowtherethrough to a relatively slow rate.

In accordance with a further preferred embodiment of the presentinvention the liquid passes through the liquid inlet channel, fills theliquid heating chamber accommodating volume and flows into the liquidheating chamber via the first and second apertures. In accordance withstill another preferred embodiment of the present invention the liquidis heated in the liquid heating chamber and a temperature of the liquidor of air overlying the liquid, depending on the liquid level of theliquid, is sensed by at least one temperature sensor. In accordance withanother preferred embodiment of the present invention the at least onetemperature sensor is mounted onto a printed circuit board which ismounted within the principal housing portion and located outside of theliquid heating chamber accommodating volume.

In accordance with another preferred embodiment of the present inventionthe heated liquid discharge system also includes control circuitry, foroperation of the main assembly, which is connected to the at least onetemperature sensor.

In accordance with yet another preferred embodiment of the presentinvention the heated liquid discharge system also includes anoverheating cut-off fuse for shutting off electrical power to at leastpart of the main assembly in the event of overheating of the liquidheating chamber. In accordance with still another preferred embodimentof the present invention the fuse is formed with an undersurface of aresilient material and is retained in tight thermal engagement with theunderside of a base of the liquid heating element.

In accordance with another preferred embodiment of the present inventionthe liquid drain aperture together with a leaky one-way valve providesboth overheating and anti-freezing protection for the main assembly.

In accordance with yet another preferred embodiment of the presentinvention when the liquid is not being pumped into the liquid heatingchamber, the liquid tends to drain slowly from the liquid heatingchamber via the leaky one-way valve until a level of liquid in theliquid heating chamber reaches the level of the liquid drain aperture,at which point air, rather than liquid is drawn into the liquid outflowconduit, effectively terminating drainage and retaining liquid insidethe liquid heating chamber accommodating volume generally at the levelof the liquid drain aperture.

In accordance with still another preferred embodiment of the presentinvention retention of liquid inside the liquid heating chamber at alevel generally not lower than that of the liquid drain aperture ensuresthat the level of liquid in the liquid heating chamber at least coversmost of the heating elements located therein, ensuring rapid heating ofthe liquid and avoiding burning out of the heating elements due to lackof the liquid in the vicinity thereof and retention of the liquid insidethe liquid heating chamber at a level no higher than that of the liquiddrain aperture ensures that sufficient freezing expansion volume isprovided so that when the vehicle is not being operated and is in afreezing environment, freezing of the liquid therein does not causecracking of the liquid heating chamber.

There is yet further provided in accordance with yet another preferredembodiment of the present invention a heated liquid discharge systemincluding a main assembly which provides liquid heating and includeselectrical and liquid flow control functionalities, a liquid inflowconduit supplying liquid from a liquid reservoir to the main assemblyand a liquid outflow conduit supplying liquid to at least one sprayerlocated at at least one location on a motor vehicle, the liquid inflowconduit having connected in series therewith a leaky one-way valve whichpermits limited backflow of liquid from the main assembly to thereservoir.

There is even further provided in accordance with yet another preferredembodiment of the present invention a heated liquid discharge systemincluding a main assembly which provides liquid heating and includeselectrical and liquid flow control functionalities, a liquid inflowconduit supplying liquid from a liquid reservoir to the main assemblyand a liquid outflow conduit supplying liquid to at least one sprayerlocated at at least one location on a motor vehicle, the main assemblyincluding a liquid heating chamber and an electrical circuit boardhaving mounted thereon a liquid temperature sensor which sensestemperature of the liquid in the liquid heating chamber.

In accordance with yet another preferred embodiment of the presentinvention the main assembly includes a liquid heating chambercommunicating with the liquid inflow conduit and the liquid outflowconduit and being formed with a liquid drain aperture located on a sidethereof which permits draining of liquid from the liquid heating chambergenerally down to level of the liquid drain aperture via the leakyone-way valve.

In accordance with yet another preferred embodiment of the presentinvention the draining takes place when a vehicle pump supplying liquidto the liquid inflow conduit is not in operation. In accordance withanother preferred embodiment of the present invention the at least onelocation includes at least one of the following locations: front vehiclewindshield, back vehicle windshield, side vehicle windows, surfacevehicle headlights, vehicle rear lights and vehicle exterior mirrors.

In accordance with still another preferred embodiment of the presentinvention a vehicle operator actuation switch is electrically coupled tothe main assembly. Alternatively or additionally, the main assembly isconnected to a vehicle computer. Additionally or alternatively, the mainassembly is connected to a vehicle ignition switch.

In accordance with yet another preferred embodiment of the presentinvention the main assembly includes a principal housing portion and acover housing portion. Additionally, the principal housing portiondefines a generally circular cylindrical liquid heating chamberaccommodating volume in a major portion of which is disposed a liquidheating assembly including the liquid heating chamber.

In accordance with still another preferred embodiment of the presentinvention the liquid heating chamber includes a generally circularcylindrical outer sleeve. Preferably, the liquid heating assemblyincludes a plurality of heating elements located within the liquidheating chamber. Additionally, electrical characteristics of individualones of the plurality of heating elements are different from each other.

In accordance with still another preferred embodiment of the presentinvention the principal housing portion defines a liquid inlet channeland a heated liquid outlet channel, both communicating with the liquidheating chamber accommodating volume and respectively communicating withthe liquid inflow conduit and the liquid outflow conduit. Additionally,the principal housing portion also defines a heated liquid temperaturesensor mounting aperture which communicates with the liquid heatingchamber accommodating volume. In accordance with yet another preferredembodiment of the present invention liquid supplied to the liquidheating chamber accommodating volume via the liquid inlet channel entersthe liquid heating chamber via at least two liquid inlet aperturesformed in the liquid heating chamber including a first aperture locatednear a base of the liquid heating chamber and a second aperture locatedat an opposite side of the liquid heating chamber from the firstaperture and near a middle of a height of the liquid heating chamber.

In accordance with yet another preferred embodiment of the presentinvention during operation of the vehicle pump supplying liquid to theliquid inflow conduit a level of the liquid exceeds the height of theliquid heating chamber and fills the liquid heating chamberaccommodating volume. Additionally, the liquid drain aperture is locatedon a side of the liquid heating chamber just below the top thereof,which permits draining of the liquid from the liquid heating chamberaccommodating volume generally only down to the level of the liquiddrain aperture when the vehicle pump is not in operation. In accordancewith another preferred embodiment of the present invention the liquidfrom the liquid reservoir is supplied by the vehicle pump via the liquidinlet conduit via a liquid inlet pathway portion of a liquid connectorassembly, which also defines a liquid outlet pathway portion.

In accordance with yet another preferred embodiment of the presentinvention the liquid connector assembly defines a differential pressurebypass pathway portion, which is controlled by a one-way valve and whichpermits liquid flow from the liquid inlet pathway portion to the liquidoutlet pathway portion when a pressure differential thereacross reachesa predetermined threshold, which indicates the existence of a blockagein a liquid path through the liquid heating chamber accommodatingvolume. In accordance with yet another preferred embodiment of thepresent invention the liquid inlet pathway portion includes a leaky oneway valve which permits supply of liquid under pressure to the liquidheating chamber accommodating volume but restricts backflow therethroughto a relatively slow rate.

In accordance with another preferred embodiment of the present inventionthe liquid passes through the liquid inlet channel, fills the liquidheating chamber accommodating volume and flows into the liquid heatingchamber via the first and second apertures.

In accordance with yet another preferred embodiment of the presentinvention the liquid is heated in the liquid heating chamber and atemperature of the liquid or of air overlying the liquid, depending onthe liquid level of the liquid, is sensed by the liquid temperaturesensor.

In accordance with yet another preferred embodiment of the presentinvention the at liquid temperature sensor is mounted onto a printedcircuit board which is mounted within the principal housing portion andlocated outside of the liquid heating chamber accommodating volume.

In accordance with yet another preferred embodiment of the presentinvention the heated liquid discharge system also includes controlcircuitry, for operation of the main assembly, which is connected to theliquid temperature sensor.

In accordance with another preferred embodiment of the present inventionthe heated liquid discharge system also includes an overheating cut-offfuse for shutting off electrical power to at least part of the mainassembly in the event of overheating of the liquid heating chamber.Preferably, the fuse is formed with an undersurface of a resilientmaterial and is retained in tight thermal engagement with the undersideof a base of the liquid heating element.

In accordance with another preferred embodiment of the present inventionthe liquid drain aperture together with the leaky one-way valve providesboth overheating and anti-freezing protection for the main assembly.

In accordance with yet another preferred embodiment of the presentinvention when the liquid is not being pumped into the liquid heatingchamber, the liquid tends to drain slowly from the liquid heatingchamber via the leaky one-way valve until a level of liquid in theliquid heating chamber reaches the level of the liquid drain aperture,at which point air, rather than liquid is drawn into the liquid outflowconduit, effectively terminating drainage and retaining liquid insidethe liquid heating chamber accommodating volume generally at the levelof the liquid drain aperture.

In accordance with still another preferred embodiment of the presentinvention retention of liquid inside the liquid heating chamber at alevel generally not lower than that of the liquid drain aperture ensuresthat the level of liquid in the liquid heating chamber at least coversmost of the heating elements located therein, ensuring rapid heating ofthe liquid and avoiding burning out of the heating elements due to lackof the liquid in the vicinity thereof and retention of the liquid insidethe liquid heating chamber at a level no higher than that of the liquiddrain aperture ensures that sufficient freezing expansion volume isprovided so that when the vehicle is not being operated and is in afreezing environment, freezing of the liquid therein does not causecracking of the liquid heating chamber.

There is yet further provided in accordance with still another preferredembodiment of the present invention a heated liquid discharge methodincluding supplying liquid from a liquid reservoir to a liquid heatingchamber included in a main assembly, heating the liquid in the liquidheating chamber, supplying heated liquid from the liquid heating chamberto at least one sprayer located at at least one location on a motorvehicle and draining of liquid to the liquid reservoir from the liquidheating chamber generally down to a predetermined level in the liquidheating chamber.

In accordance with another preferred embodiment of the present inventionthe supplying liquid from a liquid reservoir to a liquid heating chamberis via a liquid inflow conduit and the supplying heated liquid from theliquid heating chamber to the at least one sprayer located at at leastone location on a motor vehicle is via a liquid outflow conduit.Additionally or alternatively, the draining is via a liquid drainaperture located on a side of the liquid heating chamber. Preferably,the draining takes place when a vehicle pump supplying liquid to theliquid inflow conduit is not in operation.

In accordance with yet another preferred embodiment of the presentinvention the at least one location includes at least one of thefollowing locations: front vehicle windshield, back vehicle windshield,side vehicle windows, surface vehicle headlights, vehicle rear lightsand vehicle exterior mirrors.

In accordance with another preferred embodiment of the present inventionthe heated liquid discharge method also includes electrically coupling avehicle operator actuation switch to the main assembly.

In accordance with another preferred embodiment of the present inventionthe heated liquid discharge method also includes connecting the mainassembly to a vehicle computer. In accordance with another preferredembodiment of the present invention the heated liquid discharge methodalso includes connecting the main assembly to a vehicle ignition switch.

In accordance with another preferred embodiment of the present inventionthe heating the liquid in the liquid heating chamber is provided by aplurality of heating elements located within the liquid heating chamber.In accordance with another preferred embodiment of the present inventionelectrical characteristics of individual ones of the plurality ofheating elements are different from each other.

In accordance with another preferred embodiment of the present inventionthe liquid flows to the liquid heating chamber via a liquid inletchannel and enters the liquid heating chamber via at least two liquidinlet apertures formed in the liquid heating chamber including a firstaperture located near a base of the liquid heating chamber and a secondaperture located at an opposite side of the liquid heating chamber fromthe first aperture and near a middle of a height of the liquid heatingchamber.

In accordance with another preferred embodiment of the present inventionduring operation of the vehicle pump supplying liquid to the liquidinflow conduit a level of the liquid exceeds the height of the liquidheating chamber and fills a liquid heating chamber accommodating volumedefined within the liquid heating chamber.

In accordance with still another preferred embodiment of the presentinvention the liquid drain aperture is located on a side of the liquidheating chamber just below the top thereof, which permits the drainingof the liquid from the liquid heating chamber accommodating volumegenerally only down to the level of the liquid drain aperture when thevehicle pump is not in operation.

In accordance with still another preferred embodiment of the presentinvention the liquid from the liquid reservoir is supplied by thevehicle pump via the liquid inlet conduit via a liquid inlet pathwayportion of a liquid connector assembly, which also defines a liquidoutlet pathway portion.

In accordance with still another preferred embodiment of the presentinvention the heated liquid discharge method also includes controlling adifferential pressure bypass pathway portion defined within a liquidconnector assembly by a one-way valve, the one-way valve permits liquidflow from the liquid inlet pathway portion to the liquid outlet pathwayportion when a pressure differential thereacross reaches a predeterminedthreshold, which indicates the existence of a blockage in a liquid paththrough the liquid heating chamber accommodating volume.

In accordance with yet another preferred embodiment of the presentinvention the heated liquid discharge method and also includespermitting supply of liquid under pressure to the liquid heating chamberaccommodating volume but restricting backflow therethrough to arelatively slow rate.

In accordance with another preferred embodiment of the present inventionthe liquid passes through the liquid inlet channel, fills the liquidheating chamber accommodating volume and flows into the liquid heatingchamber via the first and second apertures.

In accordance with still another preferred embodiment of the presentinvention the heated liquid discharge method also includes sensing atemperature of the liquid in the liquid heating chamber or of airoverlying the liquid, depending on the liquid level of the liquid, by atleast one temperature sensor.

In accordance with still another preferred embodiment of the presentinvention the heated liquid discharge method also includes operating themain assembly by a control circuitry, for operation of the mainassembly, which is connected to the at least one temperature sensor.

In accordance with still another preferred embodiment of the presentinvention the heated liquid discharge method also includes shutting offelectrical power to at least part of the main assembly in the event ofoverheating of the liquid heating chamber by an overheating cut-offfuse. Preferably, the fuse is formed with an undersurface of a resilientmaterial and is retained in tight thermal engagement with the undersideof a base of the liquid heating element.

In accordance with yet another preferred embodiment of the presentinvention the heated liquid discharge method also includes providingboth overheating and anti-freezing protection for the main assembly bythe liquid drain aperture together with a leaky one-way valve.

In accordance with still another preferred embodiment of the presentinvention when the liquid is not being pumped into the liquid heatingchamber, the liquid tends to drain slowly from the liquid heatingchamber via the leaky one-way valve until a level of liquid in theliquid heating chamber reaches a level of the liquid drain aperture, atwhich point air, rather than liquid is drawn into the liquid outflowconduit, effectively terminating drainage and retaining liquid insidethe liquid heating chamber accommodating volume generally at the levelof the liquid drain aperture.

In accordance with still another preferred embodiment of the presentinvention retention of liquid inside the liquid heating chamber at alevel generally not lower than that of the liquid drain aperture ensuresthat the level of liquid in the liquid heating chamber at least coversmost of the heating elements located therein, ensuring rapid heating ofthe liquid and avoiding burning out of the heating elements due to lackof the liquid in the vicinity thereof and retention of the liquid insidethe liquid heating chamber at a level no higher than that of the liquiddrain aperture ensures that sufficient freezing expansion volume isprovided so that when the vehicle is not being operated and is in afreezing environment, freezing of the liquid therein does not causecracking of the liquid heating chamber.

There is also provided in accordance with still another preferredembodiment of the present invention a heated liquid discharge methodincluding supplying liquid from a liquid reservoir to a liquid heatingchamber, heating the liquid in the liquid heating chamber, supplyingheated liquid from the liquid heating chamber to at least one sprayerlocated at at least one location on a motor vehicle and draining ofliquid to the liquid reservoir from the liquid heating chamber via aleaky one-way valve.

There is further provided in accordance with yet another preferredembodiment of the present invention a heated liquid discharge methodincluding supplying liquid from a liquid reservoir to a liquid heatingchamber, heating the liquid in the liquid heating chamber, supplyingheated liquid from the liquid heating chamber to at least one sprayerlocated at at least one location on a motor vehicle, sensing atemperature of the heated liquid and separately sensing a temperature ofthe liquid heating chamber.

362. A heated liquid discharge method according to claim 361 and alsoincluding draining of the liquid to the liquid reservoir from the liquidheating chamber generally down to a predetermined level in the liquidheating chamber.

In accordance with another preferred embodiment of the present inventionthe supplying liquid from a liquid reservoir to a liquid heating chamberis via a liquid inflow conduit and the supplying heated liquid from theliquid heating chamber to the at least one sprayer located at at leastone location on a motor vehicle is via a liquid outflow conduit.

BRIEF DESCRIPTION OF THE DRAWINGS AND APPENDIX

The present invention will be understood and appreciated from thefollowing detailed description, taken in conjunction with the drawingsand appendix in which:

FIG. 1 is a simplified partially pictorial and partially schematicillustration of a heated liquid discharge system constructed andoperative in accordance with a preferred embodiment of the presentinvention installed in a motor vehicle;

FIGS. 2A and 2B are, respectively, a simplified pictorial illustrationand a simplified partially exploded view illustration of an assemblyforming part of the system of FIG. 1;

FIG. 3 is a simplified exploded view illustration of part of theassembly shown in FIGS. 2A and 2B;

FIG. 4 is a simplified exploded view illustration of a subassembly ofthe assembly shown in FIGS. 2B and 3;

FIG. 5 is a simplified illustration of one of the elements of thesubassembly shown in FIG. 4;

FIGS. 6A, 6B and 6C are, respectively, a simplified illustration ofanother embodiment of some of the elements of the subassembly shown inFIG. 4, a sectional illustration taken along lines VIB-VIB in FIG. 6Aand a partial sectional illustration taken along lines VIC-VIC in FIG.6B;

FIGS. 7A and 7B are, respectively, a simplified illustration of anotherembodiment of some of the elements of the subassembly shown in FIG. 4and a sectional illustration taken along lines VIIB-VIIB in FIG. 7A;

FIG. 8 is a sectional illustration of the subassembly shown in FIG. 4 intwo operative orientations;

FIGS. 9A and 9B are, respectively, a simplified illustration of anotherembodiment of the elements shown in FIGS. 7A & 7B and a sectionalillustration taken along lines IXB-IXB in FIG. 9A;

FIG. 10 is a sectional illustration of another embodiment of thesubassembly shown in FIG. 4 and which incorporates the embodiment ofFIGS. 9A & 9B, in two operative orientations;

FIG. 11 is a simplified timing diagram illustrating the operation of thesystem of FIGS. 1-10;

FIG. 12 is a simplified partially pictorial and partially schematicillustration of a heated liquid discharge system constructed andoperative in accordance with another preferred embodiment of the presentinvention installed in a motor vehicle;

FIGS. 13A and 13B are, respectively, a simplified pictorial illustrationand a simplified partially exploded view illustration of an assemblyforming part of the system of FIG. 12;

FIG. 14 is a simplified exploded view illustration of part of theassembly shown in FIGS. 13A and 13B;

FIG. 15 is a simplified timing diagram illustrating the operation of thesystem of FIGS. 12-14;

FIG. 16 is a simplified partially pictorial and partially schematicillustration of a heated liquid discharge system constructed andoperative in accordance with yet another preferred embodiment of thepresent invention installed in a motor vehicle;

FIGS. 17A and 17B are, respectively, a simplified pictorial illustrationand a simplified partially exploded view illustration of an assemblyforming part of the system of FIG. 16;

FIG. 18 is a simplified exploded view illustration of part of theassembly shown in FIGS. 17A and 17B;

FIG. 19 is a simplified illustration of a heated liquid discharge systemconstructed and operative in accordance with another preferredembodiment of the present invention mounted in a motor vehicle;

FIG. 20 is a simplified exploded view illustration of a portion of theheated liquid discharge system of FIG. 19;

FIGS. 21A & 21B are simplified front view and back view pictorialillustrations corresponding to FIG. 20;

FIG. 22 is a simplified sectional illustration taken along lines XXI-XXIin FIG. 21A;

FIG. 23 is a simplified sectional illustration taken along linesXXIII-XXIII in FIG. 21A; and

FIGS. 24A, 24B, 24C/1, 24C/2, 24C/3, 24D, 24E, 24F, 24G & 24H aretogether an electrical schematic illustration of the circuitry of thesystem of FIGS. 19-23.

BRIEF DESCRIPTION OF THE APPENDIX

The Appendix includes a computer listing which form a heated liquiddischarge system in accordance with a preferred software embodiment ofthe present invention when installed in accordance with installationinstructions set forth hereinbelow.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIG. 1, which is a simplified pictorialillustration of a heated liquid discharge system constructed andoperative in accordance with a preferred embodiment of the presentinvention installed in a motor vehicle. As seen in FIG. 1, an otherwiseconventional motor vehicle 100 is seen to incorporate a heated liquiddischarge system 102 constructed and operative in accordance with apreferred embodiment of the present invention. The heated liquiddischarge system preferably includes a vehicle washing liquid dischargeassembly, a vehicle surface washer assembly and a main assembly 104,which provides liquid heating as well as electrical and liquid flowcontrol functionalities. Main assembly 104 is electrically connected viaelectrical cables 106 to a vehicle battery 108. It is appreciated thatvehicle washing liquid discharge assembly and vehicle surface washingassembly are preferably a part of conventional motor vehicle 100.

A liquid inflow conduit 110 supplies washing liquid, such as water orwindshield cleaning liquid, from a vehicle liquid reservoir 112, havingan associated vehicle pump 114, to main assembly 104. Liquid inflowconduit 110 preferably includes first and second branches 116 and 118.Branch 116 is coupled to an output of vehicle pump 114, while branch 118is coupled directly to the interior of reservoir 112. Thus liquid may beobtained from reservoir 112 independently of whether vehicle pump 114 isin operation. A one-way valve 120 is preferably provided along branch118, to prevent liquid pumped by vehicle pump 114 from returning to thereservoir 112 via branch 118.

A liquid outflow conduit 122 supplies washing liquid to one or moresprayers 124, which may be located at one or more of the followingvehicle surfaces which requires washing: front vehicle windshield, backvehicle windshield, side vehicle windows in general and especially inlocations providing viewing access to vehicle exterior mirrors, vehicleheadlights, vehicle rear lights and vehicle exterior mirrors.

A vehicle operator actuation switch 130, typically located on thevehicle dashboard, is electrically coupled to main assembly 104 by acontrol conductor 132. Additional control conductors of any suitablenumber, here designated by reference numeral 134, may couple the mainassembly 104 to a vehicle computer (not shown) or to individual vehiclecomponents, such as vehicle pump 114 or vehicle windshield wipers 135.One or more sensor conductors, here designated by reference numeral 136,may couple one or more external sensors 137, such as, for example,temperature sensors, vehicle speed sensors and humidity sensors, to themain assembly 104, either directly or via the vehicle computer.

In accordance with a preferred embodiment of the present invention, mainassembly 104 may have associated therewith, typically in a subassembly140, an auxiliary pump 142 in series along the liquid inflow conduit110. Preferably, a one-way valve equipped bypass conduit 144 is providedin parallel to auxiliary pump 142 for permitting liquid ingress to mainassembly 104 along liquid outflow conduit 122, even if auxiliary pump142 fails to function. A one way valve 146 is arranged along by passconduit 144 so as to prevent backflow of the output of auxiliary pump142 in a direction away from main assembly 104.

Additionally, in accordance with a preferred embodiment of the presentinvention, a normally closed automatically operative valve, which ispreferably a differential pressure responsive one-way valve 148interconnects liquid outflow conduit 122 and liquid inflow conduit 110.Differential pressure responsive one-way valve 148 is opened when apressure difference thereacross exceeds a predetermined threshold,typically 0.3-0.5 bar, so as to enable normal operation of vehiclesprayers 124 in response to conventional vehicle actuation of vehiclepump 114, notwithstanding malfunction of the main assembly 104.

Reference is now made to FIGS. 2A and 2B, which are, respectively, asimplified pictorial illustration and a simplified partially explodedview illustration of the main assembly 104, forming part of the systemof FIG. 1. As seen in FIG. 2A, the main assembly 104 preferablycomprises a housing 200, including a base 202 and a cover 204, which arepreferably mounted onto vehicle 100 (FIG. 1) by means of a mountingbracket 206.

As seen with greater particularity in FIG. 2B, the main assembly 104comprises a liquid heating subassembly 208, which preferably includes aheat exchanger preferably in the form of a primary liquid heating volumeportion and a secondary liquid heating volume portion. Primary liquidheating volume portion and secondary liquid heating volume portion arepreferably in the form of first and second conduit elements 210 and 212,which are preferably bolted together. First and second conduit elements210 and 212 define a liquid heating enclosure which an interior thereofdefines a liquid heating volume. Preferably, mounted onto liquid heatingsubassembly 208 there is provided an electrical control subassembly 214,typically comprising an electrical circuit board 216 and a plurality ofheating elements, preferably three in number, designated by referencenumerals 218, 220 and 222. An electrical connector 224, of conventionalconstruction, provides electrical connections for control conductors 132& 134 and sensor conductor 136, which are preferably connected to padson circuit board 216. Cables 106, which provide connection to thevehicle battery 108 (FIG. 1), typically are coupled directly to thecircuit board 216. A liquid temperature sensor 226, which senses thetemperature of liquid as it leaves the liquid heating subassembly 208,is also coupled directly to the circuit board 216.

Electrical circuitry on electrical circuit board 216 provides, interalia, control of the operation of liquid heating elements 218, 220 and222, preferably by means of first and second relays 228 and 230 and aFET 232 (Field-Effect Transistor), respectively.

Communicating with first and second conduit elements 210 and 212 andwith respective liquid outflow conduit 122 and liquid inflow conduit 110are liquid outflow and liquid inflow connectors 240 and 242respectively, which are seen to be interconnected by differentialpressure responsive one-way valve 148. Auxiliary pump 142, bypassconduit 144 and one-way valve 146 are seen disposed in liquid inflowconnector 242, it being appreciated that alternatively they may belocated externally thereof.

Reference is now made to FIG. 3, which is a simplified exploded viewillustration the of part of the assembly shown in FIGS. 2A & 2B, to FIG.4, which is a simplified exploded view illustration of the liquidheating subassembly 208 shown in FIGS. 2B and 3 and to FIG. 5, which is,a simplified illustration of one of the elements of the liquid heatingsubassembly 208 shown in FIG. 4.

As seen in FIG. 3, relays 228 and 230 and FET 232, as well as otherelectrical components (not shown), are typically mounted onto printedcircuit board 216, which is, in turn, mounted onto first conduit element210, preferably by means of screws 234 and spacers 236. First conduitelement 210 is preferably formed of a good conductor, such as aluminum,and has mounted thereon, in heat exchange relationship, the threeheating elements 218, 220 and 222, preferably by means of screws 238.

Second conduit element 212 is preferably formed of a somewhat flexibleand resilient material, such as LEXAN®, and is preferably sealed as byscrews 240 to 210 and to a heat-conductive displaceable element, whichis preferably an intervening liquid impermeable diaphragm 250. Thediaphragm may be an element separate from the second conduit element, asshown in FIGS. 3, 4, 6A, 6B, 7A, 7B & 8, or alternatively may beintegrally formed with the second conduit element, as illustrated inFIGS. 9A, 9B and 10 and described hereinbelow. FIG. 4 illustratestypical general configurations of conduits defined by first and secondconduit elements 210 and 212 extending from a liquid ingress opening 252in second-conduit element 212, via a conduit 254 defined therein and viaone or more apertures 256 formed in diaphragm 250, through a conduit 258formed in first conduit element 210 and out through a heated liquidegress opening 260 formed in the first conduit element 210.

It is a particular feature of the embodiment of FIG. 5 that the conduit258 defined by the first conduit element 210 includes a plurality ofbifurcated conduit portions, including straight bifurcated portions 262and curved bifurcated portions 264. The function of the bifurcatedconduit portions 262 and 264 is to generate turbulence and generally tohelp cause the flow of liquid therethrough to be such that generally allof the liquid flowing through the first conduit element 210 is in heatexchange contact with the walls of the conduit 258 to generally the sameextent. For example, the provision of bifurcated conduit portions 262and 264 prevents the occurrence of a situation where a portion of theliquid is generally in contact with the walls of the conduit 258 whileanother portion thereof is generally not in contact with the walls ofthe conduit 258. The provision of bifurcated conduit portions isintended to enhance the speed and uniformity of liquid heating.

It is noted that conduit 258 may be configured to have side walls havinga wavy configuration so as to further enhance the speed and uniformityof liquid heating.

Reference is now made to FIGS. 6A, 6B and 6C, which are, respectively, asimplified illustration of another embodiment of some of the elements ofthe subassembly shown in FIG. 4, a sectional illustration taken alonglines VIB-VIB in FIG. 6A and a sectional illustration taken along linesVIC-VIC in FIG. 6B. Similarly to that seen in FIG. 5, a conduit 265defined by a first conduit element 266 includes a plurality ofbifurcated conduit portions, including straight bifurcated portions 267and curved bifurcated portions 268. The function of the bifurcatedconduit portions 267 and 268 is to generate turbulence and generally tohelp cause the flow of liquid therethrough to be such that generally allof the liquid flowing through the first conduit element 266 is in heatexchange contact with the walls of the conduit 265 to generally the sameextent.

In the embodiment of FIGS. 6A, 6B & 6C, a top conduit wall 269 definedby first conduit element 266 and a bottom conduit wall 270, defined by adiaphragm 271, are configured to have a wavy, toothed or otherwisenon-smooth configuration to further help cause the flow of liquidtherethrough to be turbulent and such that generally all of the liquidflowing through the first conduit element 266 is in heat exchangecontact with the walls of the conduit 265 to generally the same extent.Thus, a situation where a portion of the liquid is generally in contactwith the walls of the conduit 265 while another portion thereof isgenerally not in contact with the walls of the conduit 265 issubstantially obviated and the speed and uniformity of liquid heating iscorrespondingly enhanced.

It is noted that conduit 265 may be additionally configured to have sidewalls having a wavy configuration so as to further enhance the speed anduniformity of liquid heating.

Reference is now made to FIG. 7A, which is a simplified illustration ofone embodiment of the second conduit element 212 shown in FIGS. 2A-5, toFIG. 7B, which is a sectional illustration taken along lines VIIB-VIIBin FIG. 7A, and to FIG. 8, which is a sectional illustration of FIG. 4in two operative orientations. FIGS. 7A and 7B illustrate a relativelyresilient and flexible second conduit element 212 in association withresilient and flexible diaphragm 250. Liquid entering second conduitelement 212 at liquid ingress opening 252 travels along a labyrinthinepath defined by relatively rigid baffles 272 between a relativelyflexible and resilient base 274, preferably integrally formed withbaffles 272 and diaphragm 250. The liquid exits the second conduitelement 212 via one or more apertures 256 formed in diaphragm 250.

As illustrated particularly in FIG. 8, the provision of second conduitelement 212 provides freezing protection for the liquid heatingsubassembly 208, such that, when liquid freezes in the first conduitelement 210, its expansion causes diaphragm 250 to bow outwardly fromfirst conduit element 210 and to expand into the volume of secondconduit element 212. Accordingly, expansion of the liquid in firstconduit element 210 is accommodated without producing possible crackingor other damage to the first conduit element 210. Freezing of the liquidin the second conduit element 212 and displacement of the diaphragm 250into the volume of the second conduit element is accommodated by outwardbowing of the resilient base 274.

The structure of the liquid heating subassembly 208 as describedhereinabove, including a first conduit element 210, having heatingelements directed associated therewith, and a second conduit element212, not having heating elements directly associated therewith, butnevertheless being in a relatively slow heat exchange relationship withthe first conduit element 210, also has the advantage of providing alimited pre-heating functionality for liquid supplied from reservoir 112(FIG. 1), first to the second conduit element 212 and therefrom to thefirst conduit element 210.

It is noted that second conduit element 212 may be provided with heatingelements (not shown).

Reference is now made to FIG. 9A, which is a simplified illustration ofan alternative to the embodiment of the second conduit element 212 shownin FIGS. 2A-5, to FIG. 9B, which is a sectional illustration taken alonglines IXB-IXB in FIG. 9A, and to FIG. 10, which is a sectionalillustration of another embodiment of the subassembly shown in FIG. 4and which incorporates the embodiment of FIGS. 9A & 9B, in two operativeorientations. FIGS. 9A and 9B illustrate a relatively resilient andflexible second conduit element 282, preferably integrally formed with aresilient and flexible diaphragm 284. Liquid entering second conduitelement 282 at a liquid ingress opening 286 travels along a labyrinthinepath defined by relatively rigid baffles 288 between a relativelyflexible and resilient base 290, preferably bonded to baffles 288 anddiaphragm 284. The liquid exits the second conduit element 282 via oneor more apertures 292 formed in diaphragm 284.

As illustrated particularly in FIG. 10, the provision of second conduitelement 282 provides freezing protection for the liquid heatingsubassembly 208, in that, when liquid freezes in the first conduitelement 210, its expansion causes diaphragm 284 to bow outwardly fromfirst conduit element 210 and to expand into the volume of secondconduit element 282. Accordingly, expansion of the liquid in firstconduit element 210 is accommodated without producing possible crackingor other damage to the first conduit element 210. Freezing of the liquidin the second conduit element 282 and displacement of the diaphragm 284into the volume of the second conduit element 282 preferably isaccommodated by outward bowing of the resilient base 290.

The structure of the liquid heating subassembly 208 as describedhereinabove, including a first conduit element 210, having heatingelements directed associated therewith, and a second conduit element282, not having heating elements directly associated therewith, butnevertheless being in a relatively slow heat exchange relationship withthe first conduit element 210, also has the advantage of providing alimited pre-heating functionality for liquid supplied from reservoir 112(FIG. 1), first to the second conduit element 282 and therefrom to thefirst conduit element 210.

Reference is now made to FIG. 11, which is a simplified timing diagramillustrating the operation of the system of FIGS. 1-10. As seen in FIG.11, system actuation is preferably initiated by a user, such as thedriver of motor vehicle 100 (FIG. 1) pressing an operator actuationswitch 130, typically located on the vehicle dashboard, as seen inFIG. 1. It is noted, however, that preferably, at all times that thevehicle is running, even prior to operator actuation of switch 130, FET232 (FIGS. 2B & 3) operates heating element 222 in a continuous manner,so as to maintain liquid within the liquid heating subassembly 208 at atemperature of at least 65 degrees Centigrade, for example. If theambient temperature at the liquid heating subassembly 208 exceeds theliquid maintenance temperature, FET 232 is preferably caused toterminate or curtail operation of heating element 222 so as to avoidoverheating.

Upon user actuation of switch 130, relays 228 and 230 are preferablyoperated to operate respective heating element 218 and 220, whichprovide immediate boosted heating of the liquid within first conduitelement 210. When sensor 226 senses that the temperature of the liquidwithin the first conduit element 210 has reached a first predeterminedelevated temperature, typically 85 degrees Centigrade, one or both ofpumps 114 and 142 are operated to pump heated liquid out from the firstconduit element 210 and to cause the heated liquid to be sprayed bysprayers 124. The operation of one or both of pumps 114 and 142 causesunheated or less heated liquid from reservoir 112 to be suppliedinitially to second conduit element 212 and thereafter to first conduitelement 210 for heating thereof.

In the short term, the aforesaid operation of one or both of pumps 114and 142 causes a drop in the temperature of the liquid as measured bysensor 226. When the temperature of the liquid, as sensed by sensor 226,drops below a predetermined threshold temperature, typically 55 degreesCentigrade, operation of the pumps 114 and 142 is terminated. Whenfurther heating again raises the temperature of the liquid, sensed bysensor 226, to a second predetermined elevated temperature, preferablyless than the first predetermined threshold temperature, typically 65degrees, pump operation is resumed. This intermittent operation of oneor both pumps 114 and 142 continues for a predetermined number of cyclesor for a predetermined time duration following user actuation of switch130, typically four cycles.

It is noted that the electrical power requirements of the systemincrease substantially upon user actuation of the switch 130 and remaingenerally constant until completion of the last cycle following suchactuation.

It is additionally noted that the initial spray cycle, designated byreference numeral 300, is typically longer than the subsequent spraycycles, designated by reference numeral 302, for each user actuation ofswitch 130. It is further noted that when the user actuation of switch130 takes place immediately after initiation of operation of FET 232 andheating element 222, such as within 1-2 minutes following initialoperation of the motor vehicle 100, the initial spray cycle 300, isshorter than the initial spray cycle 304 in a case when the useractuation of switch 130 takes place significantly later than initialoperation of the motor vehicle 100.

It is additionally noted that the time delay between operator actuationof switch 130 and initiation of the initial spray cycle 300 issignificantly longer than the time delay between operation actuator ofswitch 130 and initial spray cycle 304, which is nearly instantaneous.This feature is due partially to the particular structure of the liquidheating subassembly 208 as described hereinabove, including a firstconduit element 210, having heating elements directed associatedtherewith, and a second conduit element, designated by reference numeral212 in FIGS. 2A-8 and 282 in FIGS. 9A-10, not having heating elementsdirectly associated therewith, but nevertheless being in a relativelyslow heat exchange relationship with the first conduit element 210.Liquid heating subassembly 208 also has the advantage of providing alimited pre-heating functionality for liquid supplied from reservoir112, first to the second conduit element, designated by referencenumeral 212 in FIGS. 2A-8 and 282 in FIGS. 9A-10, and therefrom to thefirst conduit element 210. The provision of the second conduit element,designated by reference numeral 212 FIGS. 2A-8 and 282 in FIGS. 9A-10,does not significantly adversely affect the speed of providing aninitial spray cycle 300 of heated liquid immediately after initialvehicle operation, but does significantly positively affect the speed ofproviding an initial spray cycle 304 of heated liquid a significant timeafter initial vehicle operation.

This beneficial functionality results from the fact that diaphragm actsas a good thermal insulator in the short term and prevents significantheat loss from the first conduit element 210 during quick heating of theliquid therein, but allows heat to pass therethrough in the long term,for heating of liquid in both the first and the second conduit elementsto the second predetermined temperature even prior to operator actuationof switch 130.

Accordingly, once the vehicle has been running for a significant time,operator actuation of switch 130 produces a nearly instantaneous initialspray cycle 304 of heated liquid and furthermore the quantity of heatedliquid which is sprayed is significantly greater, typically up to afactor of 3, than the quantity of heated liquid which is available forspraying immediately following initial vehicle operation.

Reference is now made to FIG. 12, which is a simplified pictorialillustration of a heated liquid discharge system constructed andoperative in accordance with a preferred embodiment of the presentinvention installed in a motor vehicle. As seen in FIG. 12, an otherwiseconventional motor vehicle 1100 is seen to incorporate a heated liquiddischarge system 1102 constructed and operative in accordance with apreferred embodiment of the present invention. The heated liquiddischarge system preferably includes a main assembly 1104, whichprovides liquid heating as well as electrical and liquid flow controlfunctionalities. Main assembly 1104 is electrically connected viaelectrical cables 1106 to a vehicle battery 1108.

A liquid inflow conduit 1110 supplies washing liquid, such as water orcleaning liquid, from a vehicle liquid reservoir 1112, having anassociated vehicle pump 1114, to main assembly 1104. Liquid inflowconduit 1110 preferably includes first and second branches 1116 and1118. Branch 1116 is coupled to an output of vehicle pump 1114, whilebranch 1118 is coupled directly to the interior of reservoir 1112. Thusliquid may be obtained from reservoir 1112 independently of whethervehicle pump 1114 is in operation. A one-way valve 1120 is preferablyprovided along branch 1118, to prevent liquid pumped by vehicle pump1114 from returning to the reservoir 1112 via branch 1118.

A liquid outflow conduit 1122 supplies washing liquid to one or morevehicle radar antenna sprayers 1124 operative to discharge liquid ontoan external surface of a vehicle radar antenna 1126, typicality locatedbetween vehicle headlights.

A vehicle radar actuation switch 1130, typically located on the vehicledashboard, is electrically coupled to main assembly 1104 by a controlconductor 1132. Additional control conductors of any suitable number,here designated by reference numeral 1134, may couple the main assembly1104 to a vehicle computer (not shown) or to individual vehiclecomponents, such as vehicle pump 1114 or a vehicle radar unit 1135. Oneor more sensor conductors, here designated by reference numeral 1136,may couple one or more external sensors 1137, such as, for example,temperature sensors, vehicle speed sensors and humidity sensors to themain assembly 1104, either directly or via the vehicle computer. A radarantenna spray control conductor 1138 couples the main assembly 1104 toan automatic gain control circuit (AGC) forming part of the vehicleradar unit 1135.

In accordance with a preferred embodiment of the present invention, mainassembly 1104 may include, typically in a subassembly 1140, an auxiliarypump 1142 in series along the liquid inflow conduit 1110. Preferably, aone-way valve equipped bypass conduit 1144 is provided in parallel toauxiliary pump 1142 for permitting liquid ingress to main assembly 1104along liquid inflow conduit 1110, even if auxiliary pump 1142 fails tofunction. A one way valve 1146 is arranged along bypass conduit 1144 soas to prevent backflow of the output of auxiliary pump 1142 in adirection away from main assembly 1104.

Additionally, in accordance with a preferred embodiment of the presentinvention, a differential pressure responsive one-way valve 1148interconnects liquid outflow conduit 1122 and liquid inflow conduit1110. Differential pressure responsive one-way valve 1148 is opened whena pressure difference thereacross exceeds a predetermined threshold,typically, 0.3-0.5 bar, so as to enable normal operation of vehicleradar antenna sprayers 1124, notwithstanding malfunction of the mainassembly 1104.

Reference is now made to FIGS. 13A and 13B, which are, respectively, asimplified pictorial illustration and a simplified partially explodedview illustration of the main assembly 1104, forming part of the systemof FIG. 12. As seen in FIG. 13A, the main assembly preferably comprisesa housing 1200, including a base 1202 and a cover 1204, which arepreferably mounted onto vehicle 1100 (FIG. 12) by means of a mountingbracket 1206.

As seen with greater particularity in FIG. 13B, the main assembly 1104comprises a liquid heating subassembly 1208, which preferably includesfirst and second conduit elements 1210 and 1212, which are preferablybolted together. Preferably, mounted onto liquid heating subassembly1208 there is provided an electrical control subassembly 1214, typicallycomprising an electrical circuit board 1216 and a heating element 1222.An electrical connector 1224, of conventional construction, provideselectrical connections for control conductors 1132, 1134 and 1138 andsensor conductor 1136, which are preferably connected to pads on circuitboard 1216. Cables 1106, which provide connection to the vehicle battery1108 (FIG. 12), typically are coupled directly to the circuit board1216. A liquid temperature sensor 1226, which senses the temperature ofliquid as it leaves the liquid heating subassembly 1208, is also coupleddirectly to the circuit board 1216.

Electrical circuitry on electrical circuit board 1216 provides, interalia, control of the operation of liquid heating element 1222,preferably by means of a FET 1232.

Communicating with first and second conduit elements 1210 and 1212 andwith respective liquid outflow conduit 1122 and liquid inflow conduit1110 are liquid outflow and liquid inflow connectors 1240 and 1242respectively, which are seen to be interconnected by differentialpressure responsive one-way valve 1148. Auxiliary pump 1142, bypassconduit 1144 and one-way valve 1146 are seen disposed in liquid inflowconnector 1242, it being appreciated that alternatively they may belocated externally thereof.

Reference is now made to FIG. 14, which is a simplified exploded viewillustration of part of the assembly shown in FIGS. 13A & 13B. As seenin FIG. 14, FET 1232 as well as other electrical components (not shown)are typically mounted onto printed circuit board 1216, which is, inturn, mounted onto first conduit element 1210, preferably by means ofscrews 1234 and spacers 1236. First conduit element 1210 is preferablyformed of a good conductor, such as aluminum and has mounted thereon, inheat exchange relationship, heating element 1222 preferably by means ofscrews 1238.

Second conduit element 1212 is preferably formed of a somewhat flexibleand resilient material, such as LEXAN®, and is preferably sealed as byscrews 1240 to first conduit element 1210 and to an intervening liquidimpermeable diaphragm 1250. Conduits defined by first and second conduitelements 1210 and 1212 extend from a liquid ingress opening 1252 insecond conduit element 1212, via a conduit 1254 defined therein and viaone or more apertures 1256 formed in diaphragm 1250, through a conduit(not shown) formed in first conduit element 1210 and out through aheated liquid egress opening 1260 formed in the first conduit element1210.

It is appreciated that the liquid flow in liquid heating subassembly1208 is identical to the liquid flow described hereinabove in FIGS.5-10.

Reference is now made to FIG. 15, which is a simplified timing diagramillustrating the operation of the system of FIGS. 12-14. As seen in FIG.15, liquid discharge from vehicle radar antenna sprayers 1124 on vehicleradar antenna 1126 is preferably automatically controlled. When thevehicle is running and when vehicle radar actuation switch 1130 is in anoperative orientation (FIG. 12), accumulation of deposits on the vehicleradar antenna 1126, such as slush, mud, rain, and snow cause the AGC toactivate the heated liquid discharge system (FIGS. 12-14) as describedhereinbelow.

Preferably, at all times that the vehicle is running, even when thevehicle radar is not activated, FET 1232 (FIGS. 13B & 14) operatesheating element 1222 in a continuous manner, so as to maintain liquidwithin the liquid heating subassembly 1208 preferably at a temperatureof at least 65 degrees Centigrade, for example. If the ambienttemperature at the liquid heating subassembly 1208 exceeds the liquidmaintenance temperature, FET 1232 is preferably caused to terminate orcurtail operation of heating element 1222 so as to avoid overheating.

When the AGC provides a signal of at least a predetermined thresholdvalue, here designated by reference numeral 1300, due to accumulationson the vehicle radar antenna 1126, one or both of pumps 1114 and 1142are operated to pump heated liquid out from the first conduit element1210 and to cause the heated liquid to be sprayed by vehicle radarantenna sprayers 1124. The operation of one or both of pumps 1114 and1142 causes unheated or less heated liquid from reservoir 1112 to besupplied initially to second conduit element 1212 and thereafter tofirst conduit element 1210 for heating thereof. When the value of theAGC output signal drops below another predetermined threshold value,designated by reference numeral 1302, which is typically below thresholdvalue 1300, operation of the pumps 1114 and 1142 is terminated.

In the short term, the operation of one or both of pumps 1114 and 1142causes a drop in the temperature of the liquid as measured by sensor1226. When the temperature of the liquid, as sensed by sensor 1226,drops below a predetermined threshold temperature, typically 55 degreesCentigrade, operation of the pumps 1114 and 1142 is terminated. Whenfurther heating again raises the temperature of the liquid, sensed bysensor 1226, to a predetermined elevated temperature, typically 65degrees, pump operation is resumed. This intermittent operation of oneor both pumps 1114 and 1142 continues typically until the value of theAGC signal drops below predetermined threshold value 1302.

It is noted that the electrical power requirements of the systemincrease substantially with increased accumulation and corresponding AGCcontrolled actuation of the heated liquid discharge system and remaingenerally constant until completion of the last cycle following suchactuation.

It is additionally noted that the initial spray cycle, designated byreference numeral 1310, is typically longer than the subsequent spraycycles, designated by reference numeral 1312, for AGC controlledactuation of the heated liquid discharge system. It is further notedthat when AGC controlled actuation of the heated liquid discharge systemtakes place immediately after initiation of operation of FET 1232 andheating element 1222, such as within 1-2 minutes following initialoperation of the motor vehicle 1100, the initial spray cycle 1310, isshorter than the initial spray cycle 1314 in a case when AGC controlledactuation of the heated liquid discharge system takes placesignificantly later than initial operation of the motor vehicle 1100.

It is further noted that the time delay between AGC controlled actuationof the heated liquid discharge system and initiation of the initialspray cycle 1310 is significantly longer than the time delay between AGCcontrolled actuation of the heated liquid discharge system and initialspray cycle 1314, which is nearly instantaneous. This feature is duepartially to the particular structure of the liquid heating subassembly1208 as described hereinabove, including a first conduit element 1210,having a heating element 1222 directed associated therewith, and asecond conduit element 1212 not having a heating element directlyassociated therewith, but nevertheless being in a relatively slow heatexchange relationship with the first conduit element 1210.

Liquid heating subassembly 1208 also has the advantage of providing alimited pre-heating functionality for liquid supplied from reservoir1112, first to the second conduit element 1212 and therefrom to thefirst conduit element 1210. The provision of the second conduit element1212 does not significantly adversely affect the speed of providing aninitial spray cycle 1310 of heated liquid immediately after initialvehicle operation, but does significantly positively affect the speed ofproviding an initial spray cycle 1314 of heated liquid a significanttime after initial vehicle operation.

This beneficial functionality results from the fact that diaphragm 1250acts as a good thermal insulator in the short term and preventssignificant heat loss from the first conduit element 1210 during quickheating of the liquid therein, but allows heat to pass therethrough inthe long term, for heating of liquid in both the first and the secondconduit elements to the predetermined elevated temperature even prior toAGC controlled actuation of the heated liquid discharge system.

Accordingly, once the vehicle has been running for a significant time,operator actuation of vehicle radar actuation switch 1130 produces anearly instantaneous initial spray cycle 1304 of heated liquid andfurthermore the quantity of heated liquid which is sprayed issignificantly greater, typically up to a factor of 3, than the quantityof heated liquid which is available for spraying immediately followinginitial vehicle operation.

Reference is now made to FIG. 16, which is a simplified pictorialillustration of a heated liquid discharge system constructed andoperative in accordance with a preferred embodiment of the presentinvention installed in a motor vehicle. As seen in FIG. 16, an otherwiseconventional motor vehicle 2100 is seen to incorporate a heated liquiddischarge system 2102 constructed and operative in accordance with apreferred embodiment of the present invention. The heated liquiddischarge system preferably includes a main assembly 2104, whichprovides liquid heating as well as electrical and liquid flow controlfunctionalities. Main assembly 2104 is electrically connected viaelectrical cables 2106 to a vehicle battery 2108.

A liquid inflow conduit 2110 supplies washing liquid, such as water orcleaning liquid, from a vehicle liquid reservoir 2112, having anassociated vehicle pump 2114, to main assembly 2104. A vehicle computer2115 governs the operation of the pump 2114 via a control conductor2116. Liquid inflow conduit 2110 preferably includes first and secondbranches 2117 and 2118. Branch 2117 is coupled to an output of vehiclepump 2114, while branch 2118 is coupled directly to the interior ofreservoir 2112. Thus liquid may be obtained from reservoir 2112independently of whether vehicle pump 2114 is in operation. A one-wayvalve 2120 is preferably provided along branch 2118, to prevent liquidpumped by vehicle pump 2114. from returning to the reservoir 2112 viabranch 2118.

A liquid outflow conduit 2122 supplies washing liquid to one or morewindshield sprayers 2124 operative to discharge liquid onto a vehiclewindshield 2126.

In accordance with a preferred embodiment of the present invention, mainassembly 2104 may have associated therewith, typically in a subassembly2130, an auxiliary pump 2132 in series along the liquid inflow conduit2110. Preferably, a one-way valve equipped bypass conduit 2134 isprovided in parallel to auxiliary pump 2132 for permitting liquidingress to main assembly 2104 along liquid inflow conduit 2110, even ifauxiliary pump 2132 fails to function. A one way valve 2136 is arrangedalong bypass conduit 2134 so as to prevent backflow of the output ofauxiliary pump 2132 in a direction away from main assembly 2104.

Additionally, in accordance with a preferred embodiment of the presentinvention, a differential pressure responsive one-way valve 2138interconnects liquid outflow conduit 2122 and liquid inflow conduit2110. Differential pressure responsive one-way valve 2138 is opened whena pressure difference thereacross exceeds a predetermined threshold,typically, 0.3-0.5 bar, so as to enable normal operation of windshieldsprayers 2124 and vehicle radar antenna sprayers 2140 in response toconventional vehicle actuation of vehicle pump 2114, notwithstandingmalfunction of the main assembly 2104.

A user operated vehicle unheated liquid windshield discharge actuator2142, typically located in the vicinity of the vehicle steering wheel,is electrically coupled to vehicle computer 2115 by a control conductor2150. In a first mode of operation, wherein the heated liquid dischargesystem 2102 is not user actuated for spraying heated liquid onto theradar antenna, operation of user operated vehicle unheated liquidwindshield discharge actuator 2142 by a user preferably causes anelectrical signal to be transmitted via control conductor 2150 tovehicle computer 2115, which causes activation, by means of controlconductor 2116, of vehicle pump 2114. Liquid outflow conduit 2122supplies liquid from pump 2114 and/or pump 2132 to windshield sprayers2124 via a conduit branch 2152, a normally-open valve 2154 and a conduitbranch 2156. Liquid supplied by vehicle pump 2114 and/or pump 2132 viaoutflow conduit 2122 is also supplied to windshield sprayers 2124 via abidirectional valve 2158, a conduit branch 2160 and conduit branch 2156.Bidirectional valve 2158 is normally open for liquid flow from conduit2122 to conduit branch 2160 and is electrically coupled to main assembly2104 via control conductor 2161. A one way valve 2162 preferably isprovided along conduit branch 2160, so as to prevent flow of liquid awayfrom windshield sprayers 2124.

A user operated heated liquid windshield discharge actuator 2170,typically located on the vehicle dashboard, is electrically coupled tomain assembly 2104 via a control conductor 2172. Actuation by a user ofuser operated heated liquid windshield discharge actuator 2170 causesheated liquid from main assembly 2104 to be supplied via conduit branch2152, normally-open valve 2154 and conduit branch 2156 as well as viabidirectional valve 2158 to windshield sprayers 2124 via conduitbranches 2160 and 2156.

Heated liquid from main assembly 2104 is also supplied to one or morevehicle radar antenna sprayers 2140 in response to an AGC actuationsignal received by vehicle computer 2115 from a vehicle radar unit 2173.In response to receipt of the AGC actuation signal, the vehicle computer2115 causes main assembly 2104 to provide a direction switch electricalsignal along a control conductor 2174 to bidirectional valve 2158,causing it to direct liquid from conduit 2122 along a conduit branch2176, via a flow restrictor 2178 arranged in series therewith to vehicleradar antenna sprayers 2140. Additionally, in response to receipt of theAGC actuation signal, the vehicle computer 2115 causes main assembly2104 to provide a valve closing signal to normally open valve 2154 alonga control conductor 2182. Alternatively, the AGC actuation signal issupplied directly to the main assembly 2104.

It is appreciated that in a preferred embodiment of the presentinvention, main assembly 2104 supplies heated liquid to vehicle radarantenna sprayers 2140 only when windshield sprayers 2124 are not

It is a particular feature of the present invention that if during radarantenna spraying operation of the system in response to the AGCactuation signal, either of actuators 2142 and 2170 are actuated by auser, liquid, heated or unheated as the case may be, is immediatelydirected to windshield sprayers 2124. In the case of actuation of useroperated unheated fluid windshield discharge actuator 2142, this ispreferably effected by opening of a relay 2184, which is connected inseries along control conductor 2182, in response to a relay open signalsupplied by vehicle computer 2115 along control conductor 2185, forpreventing the valve closing signal from reaching normally open valve2154, thereby retaining normally open valve 2154 in an open orientationand permitting liquid flow therethrough from conduit 2122 via conduitbranch 2152, normally open valve 2154 and conduit branch 2156 towindshield sprayers 2124. In the case of actuation of user operatedvehicle heated fluid windshield discharge actuator 2170, this ispreferably effected by main assembly 2104 not providing a valve closingsignal to normally open valve 2154 along control conductor 2182. Heatedliquid from main assembly 2104 is thus supplied to windshield sprayers2124 as described hereinabove. In both cases the operation of flowrestrictor 2178 ensures that liquid reaches windshield sprayers 2124.

A vehicle radar actuation switch 2190, typically located on the vehicledashboard, is electrically coupled to main assembly 2104 by a controlconductor 2192. One or more sensor conductors, here designated byreference numeral 2194, may couple one or more external sensors 2196,such as, for example, temperature sensors, vehicle speed sensors andhumidity sensors to the main assembly 2104, either directly or via thevehicle computer 2115.

Reference is now made to FIGS. 17A and 17B, which are, respectively, asimplified pictorial illustration and a simplified partially explodedview illustration of the main assembly 2104, forming part of the systemof FIG. 16. As seen in FIG. 17A, the main assembly 2104 preferablycomprises a housing 2200, including a base 2202 and a cover 2204, whichare preferably mounted onto vehicle 2100 (FIG. 16) by means of amounting bracket 2206.

As seen with greater particularity in FIG. 17B, the main assembly 2104comprises a liquid heating subassembly 2208, which preferably includesfirst and second conduit elements 2210 and 2212, which are preferablybolted together. Preferably, mounted onto liquid heating subassembly2208 there is provided an electrical control subassembly 2214, typicallycomprising an electrical circuit board 2216 and heating elements 2218,2220 and 2222. An electrical connector 2224, of conventionalconstruction, provides electrical connections for control conductors2182, 2161, 2172, and 2194 and sensor conductors 2192, which arepreferably connected to pads on circuit board 2216. Cables 2106, whichprovide connection to the vehicle battery 2108 (FIG. 16), typically arecoupled directly to the circuit board 2216. A liquid temperature sensor2226, which senses the temperature of liquid as it leaves the liquidheating subassembly 2208, is also coupled directly to the circuit board2216.

Electrical circuitry on electrical circuit board 2216 provides, interalia, control of the operation of liquid heating elements 2218, 2220 and2222, preferably by means of first and second relays 2228 and 2230 and aFET 2232, respectively.

Communicating with first and second conduit elements 2210 and 2212 andwith respective liquid outflow conduit 2122 and liquid inflow conduit2110 are liquid outflow and liquid inflow connectors 2240 and 2242respectively, which are seen to be interconnected by differential valve2138. Auxiliary pump 2132, bypass conduit 2134 and one-way valve 2136are seen disposed in liquid inflow connector 2242, it being appreciatedthat alternatively they may be located externally thereof.

Reference is now made to FIG. 18, which is a simplified exploded viewillustration of part of the assembly shown in FIGS. 17A & 17B. As seenin FIG. 18, relays 2228 and 2230 and FET 2232 as well as otherelectrical components (not shown) are typically mounted onto printedcircuit board 2216, which is, in turn, mounted onto first conduitelement 2210, preferably by means of screws 2234 and spacers 2236. Firstconduit element 2210 is preferably formed of a good conductor, such asaluminum and has mounted thereon, in heat exchange relationship, thethree heating elements 2218, 2220 and 2222 preferably by means of screws2238.

Second conduit element 2212 is preferably formed of a somewhat flexibleand resilient material, such as LEXAN®, and is preferably sealed as byscrews 2240 to first conduit element 2210 and to an intervening liquidimpermeable diaphragm 2250. Conduits defined by first and second conduitelements 2210 and 2212 extend from a liquid ingress opening 2252 insecond conduit element 2212, via a conduit 2254 defined therein and viaone or more apertures 2256 formed in diaphragm 2250, through a conduit(not shown) formed in first conduit element 2210 and out through aheated liquid egress opening 2260 formed in the first conduit element2210.

It is appreciated that the liquid flow in liquid heating subassembly2208 is identical to the liquid flow described hereinabove in FIGS.5-10.

Reference is now made to FIG. 19, which is a simplified illustration ofa heated liquid discharge system constructed and operative in accordancewith another preferred embodiment of the present invention mounted in amotor vehicle. As seen in FIG. 19, an otherwise conventional motorvehicle 3100 is seen to incorporate a heated liquid discharge system3102 constructed and operative in accordance with a preferred embodimentof the present invention. The heated liquid discharge system preferablyincludes a main assembly 3104, which provides liquid heating as well aselectrical and liquid flow control functionalities. Main assembly 3104is electrically connected via electrical cables 3106 and 3107 to avehicle battery 3108.

A liquid inflow conduit 3110 supplies liquid, such as water orwindshield cleaning liquid, from a vehicle liquid reservoir 3112, havingan associated vehicle pump 3114, to main assembly 3104.

A liquid outflow conduit 3122 supplies liquid to one or more sprayers3124, which may be located at one or more of the following vehiclelocations: front vehicle windshield, back vehicle windshield, sidevehicle windows in general and especially in locations providing viewingaccess to vehicle exterior mirrors, vehicle headlights, vehicle rearlights and vehicle exterior mirrors.

A vehicle operator actuation switch 3130, typically located on thevehicle dashboard, is electrically coupled to main assembly 3104 by acontrol conductor pair 3132. A pair of vehicle computer interfaceconductors 3134 and 3136 interconnect the main assembly 3104 to theexisting vehicle computer 3138. An ignition interface conductor 3140interconnects the main assembly 3104 to the existing vehicle ignitionswitch.

Reference is now made additionally to FIGS. 20, 21A, 21B, 22 and 23,which illustrate details of the structure and mounting of main assembly3104. The main assembly 3104 is preferably mounted onto the vehiclechassis by a suitable mounting bracket, such as mounting bracket 3142.Mounting bracket 3142 preferably comprises suitably apertured chassismounting portions 3144 and 3146 and a slide and snap fit main assemblysupport portion 3148 having slidable engagement indents 3150 and a snapfit engagement protrusion 3152 having indents 3154. The snap fitengagement protrusion 3152 may be injection molded of plastic directlyonto the remainder of mounting bracket 3142.

Main assembly 3104 comprises a liquid heating chamber communicating withliquid inflow conduit 3122 and liquid outflow conduit 3110 a principalhousing portion 3160, which is configured for removable snap-fitengagement therewith by a cover housing portion 3162. As seenparticularly in FIG. 21B, the back surface of principal housing portion3160 is formed with suitably undercut retaining protrusions 3164 whichslidably engage corresponding corners 3166 of support portion 3148underlying indents 3150. As seen particularly in FIG. 21A, the topsurface of principal housing portion 3160 is formed with a pair ofengagement guides 3168 and inclined snap fit engagement protrusions 3170which engage indents 3154 in snap fit engagement protrusion 3152.

Principal housing portion 3160 defines a generally circular cylindricalliquid heating chamber accommodating volume 3180, in a major portion ofwhich is disposed a liquid heating assembly 3182. Liquid heatingassembly 3182 preferably comprises a circular cylindrical outer sleeve3184 having a base 3186, which defines a sealing ring retaining socket3188, arranged to retain an insulative liquid sealing ring 3190.

A plurality of folded over heating elements, preferably three in number,designated by reference numerals 3192, 3194 and 3196, are located withinsleeve 3184. Preferably heating elements 3192 and 3194 partially overlieheating element 3196, as seen in FIG. 23. Each of the folded overheating elements 3192, 3194 and 3196 preferably includes a resistanceheating element 3198, located within a heating element conductive sleeve3200 and electrically insulated therefrom by an insulator 3202, such asa ceramic material.

The resistance heating element 3198 is preferably coupled at one endthereof to an electrical connection terminal 3204 extending outwardly ofbase 3186 and is coupled at an opposite end thereof to conductive sleeve3200. The conductive sleeves 3200 of each of the folded over heatingelements 3192, 3194 and 3196 are electrically coupled to ground via base3186 and an electric connector 3206. It is appreciated that theelectrical characteristics of the resistance heating elements 3198 ofthe various folded over heating elements 3192, 3194 and 3196 aretypically different from each other.

Principal housing portion 3160 also defines a liquid inlet channel 3210and a heated liquid outlet channel 3212, both communicating with liquidheating chamber accommodating volume 3180, as well as a heated liquidtemperature sensor mounting aperture 3214, also communicating withliquid heating chamber accommodating volume 3180. Liquid supplied toliquid heating chamber accommodating volume 3180 via liquid inletchannel 3210 preferably enters a liquid heating chamber 3216, defined bythe interior of sleeve 3184, via at least two liquid inlet aperturesformed in sleeve 3184, preferably a first aperture 3218 located near thebase 3816 and a second aperture 3220, preferably located at an oppositeside of sleeve 3184 and near the middle of the height of the sleeve3184.

Normally, during operation of pump 3114 (FIG. 19), the level of theliquid exceeds the height of the liquid heating chamber and fills theliquid heating chamber accommodating volume 3180. A liquid drainaperture 3228 is located on a side of sleeve 3184 just below the topthereof, which permits draining of liquid from volume 3180 only down tothe level of liquid drain aperture 3228, when the vehicle pump 3114(FIG. 19) is not in operation. The importance of liquid drain aperture3228 and its placement in the liquid heating chamber accommodatingvolume 3180 will be described hereinbelow.

Liquid from reservoir 3112 (FIG. 19) is supplied by vehicle pump 3114via liquid inlet conduit 3110 via a liquid inlet pathway portion 3250 ofa liquid connector assembly 3252, which also defines a liquid outletpathway portion 3254. Liquid connector assembly 3252 preferablycomprises an injection molded element which also defines a differentialpressure bypass pathway portion 3256, which is controlled by a springloaded one-way valve 3258 and which permits liquid flow from liquidinlet pathway portion 3250 to liquid outlet pathway portion 3254 whenthe pressure differential thereacross reaches a predetermined threshold,typically 0.3-0.5 bar, which indicates the existence of a blockage inthe liquid path through valve 3260 and the liquid heating chamberaccommodating volume 3180.

Liquid inlet pathway portion 3250 preferably comprises a leaky one wayvalve 3260, preferably having a channel 3262 formed in a valve seat 3264thereof, as shown in detail in FIG. 22. Valve 3260 preferably permitssupply of liquid under pressure to the liquid heating chamberaccommodating volume 3180 but restricts backflow therethrough to arelatively slow rate. The liquid passes through liquid inlet channel3210 and fills the liquid heating chamber accommodating volume 3180. Theliquid flows into liquid heating chamber 3216 via first and secondapertures 3218 and 3220 in sleeve 3184.

The liquid is heated in liquid heating chamber 3216 and the temperatureof the liquid or the air overlying the liquid, depending on the liquidlevel, is sensed by a temperature sensor 3270, commercially availablefrom EPCOS AG. Corporate Communications of Munich, Germany, identifiedby Catalog No. G560/50K/F2 and located in heated liquid temperaturesensor mounting aperture 3214. Temperature sensor 3270 preferably ismounted onto a printed circuit board 3272 which is mounted withinprincipal housing portion 3160 and located outside of liquid heatingchamber accommodating volume 3180.

Mounted on printed circuit board 3272 is control circuitry for operationof the main assembly 3104 which is connected inter alia to temperaturesensor 3270 and via a connector 3274 and a wire harness 3276 including aconnector 3278 to control conductor pair 3132, vehicle computerinterface conductors 3134 and 3136 and ignition interface conductor 3140(FIG. 19). Electrical cables 3106 and 3107 connect the vehicle battery3108 (FIG. 19) to connection terminals 3280 of a plurality of relays3282, which supply electrical power to electrical connection terminals3204 of heating elements 3192, 3194 and 3196 via electrical connectors3284. Relays 3282 are commercially available from TYH Enterprise Limitedof Tsuen Wan, N.T., Hong Kong. Electrical connector 3206 provides adirect ground connection between base 3186 and the vehicle ground viaone of electrical cables 3106 and 3107. An overheating cut-off fuse 3290is also mounted onto printed circuit board 3272 and is connected to thecontrol circuitry for shutting off power to the heating elements 3192,3194 and 3196 in the event of overheating of the liquid heating assembly3182. Fuse 3290 is preferably formed with an undersurface of a resilientmaterial and is preferably retained in tight thermal engagement with theunderside of base 3186 by a cover element 3292.

It is a particular feature of the present invention that the provisionof liquid drain aperture 3228 in sleeve 3184 together with leaky one-wayvalve 3260 provides both overheating and anti-freezing protection forthe main assembly 3104. This synergetic functionality may be understoodby considering the operation of the system following completion of aspray cycle. At this time, due to deactivation of pump 3114, liquid isnot being pumped into liquid heating chamber accommodating volume 3180and the liquid tends to drain slowly from volume 3180 via channel 3262,leaky one-way valve 3260, liquid inlet pathway portion 3250, liquidinlet conduit 3110 and vehicle pump 3114 to reservoir 3112. Suchdrainage continues until the level of liquid in liquid heating chamberaccommodating volume 3180 reaches the level of liquid drain aperture3228, at which point air, rather than liquid is drawn into channel 3262,effectively terminating drainage and retaining liquid inside liquidheating chamber accommodating volume 3180 at the level of liquid drainaperture 3228.

Retention of liquid inside liquid heating chamber accommodating volume3180 at a level preferably not lower than that of liquid drain aperture3228 ensures that the level of liquid in liquid heating chamber 3216 atleast covers most of the heating elements 3192, 3194 and 3196, ensuringrapid heating of the liquid at the next heating cycle and avoidingburning out of the heating elements due to lack of liquid in thevicinity thereof. At the same time retention of liquid inside liquidheating chamber accommodating volume 3180 at a level preferably nohigher than that of liquid drain aperture 3228 ensures that sufficientfreezing expansion volume is provided within volume 3180 and within theliquid heating chamber 3216 so that when the vehicle is not beingoperated and is in a freezing environment, freezing of the liquidtherein does not cause cracking of the liquid heating chamber 3216 or ofthe liquid heating chamber accommodating volume 3180.

Reference is now made to FIGS. 24A, 24B, 24C/1, 24C/2, 24C/3, 24D, 24E,24F, 24G & 24H, which are together a self-explanatory electricalschematic illustration of the circuitry incorporated on PCB 3272 of thesystem of FIGS. 19-23. FIGS. 24A, 24B, 24C/1, 24C/2, 24C/3, 24D, 24E,24F, 24G & 24H indicate interconnections of the circuitry on PCB 3272with various elements of the system of FIGS. 19-23, whose referencenumbers are indicated in parenthesis in FIGS. 24A-24H. The circuitry ofFIGS. 24A-24H operates preferably using software contained in theAppendix. Table I contains a list of parts used in the circuitry shownin FIGS. 24A-24H. TABLE I Reference PCB Designator(s) Part ManufacturerPart Number Footprint C1, C2, C4, 0.01 uF, 100 V AVX Corp., SC,06031C103MAT4A 0603 C12, C24, C26, USA C29, C30 C3, C7, C10, 0.1 uF, 100V AVX Corp., SC, 12061C104MAT4A 1206 C15, C19, USA C22 C6, C9, C16, 1000pF, AVX Corp., SC, 06031C102MAT4A 0603 C20, C21, C23, 100 V USA C25,C27, C28 C8, C13, C14, 0.1 uF, 10 V AVX Corp., SC, 0603ZC104MAT4A 0603C17, C18, C31, USA C32 C5A, C5B, 1 uF, 10 V AVX Corp., SC,0805ZC106KAT4A 0805 C11 USA C33 10 uF, 35 V KEMET Electronics,T491C106M035AS “C package” Simpsonville, SC or 6032 D1, D3, D6 FastDiodes Inc., RS1D SMA Switching Westlake Village, Rectifier CA, USA D9,D12 General Diodes Inc., S1D SMA Purpose Westlake Village, Rectifier CA,USA D5, D7, D13, Schottky Semiconductor MBR0540 SOD123 D14, D17 BarrierDiode Corp., Santa Clara, CA. USA D2, D4, D15, 15 V, 500 mW,Semiconductor MMSZ5245BT1 SOD123 D16 Zener Corp., Santa Clara, CA. USAD8, D18 5.1 V, Semiconductor MMSZ5231BT1 SOD123 500 mW, Corp., SantaClara, Zener CA. USA D19, D20 DUAL Semiconductor BAV99LT1 SOT-23SWITCHING Corp., Santa Clara, DIODE CA. USA FU1 Thermal Cut ThermtrolCorp., N6 THRU Off 140 C North Canton, OH, USA JP1 5 Pin Locking MolexInc. Downers MOLEX043650-0527 MOLEX043650- Connector Grove, IL, USA 0527JP2 8 Pin Header Molex Inc. Downers 10-89-1081 THRU Grove, IL, USA K1RELAY TYH Enterprise HG4520-012-H1S RELAY-HG Limited, N.T., Hong 4520Kong K2 RELAY TYH Enterprise HG4119-012-1H11-1A RELAY-HG Limited, N.T.,Hong 4119 Kong L1, L2 Ferrite Bead, Murata BLM21AG102SN1B 0805 600ohm @Manufacturing Co., 100 MHz Ltd., Nagaokakyo-shi, Kyoto Q1, Q2 P ChannelInternational IRFL9110 SOT-223 MOSFET, Rectifier, El 100 V Segundo, CA,USA Q3, Q6, Q7 NPN Zetex plc, Oldham, FMMT614 SOT-23 Darlington, UK 100V Q4, Q5 Protected N STMicroelectronics, VNN1NV0413TR SOT-223 ChannelEast Bell Road, AZ, MOSFET USA N1 Temperature EPCOS AG. G560/50K/F2 THRUSensor Corporate Communications, Munich, Germany N2 Temperature EPCOSAG. G560/50K/F2 THRU Sensor Corporate Communications, Munich, GermanyR11 0 OHM KOA Speer RM73Z1JLTDD 0603 Electronics Inc., Bradford, PA, USAR25 1.5k, 5%, KOA Speer RK73B2ELTDD152J 1210 500 mW Electronics Inc.,Bradford, PA, USA R1, R5, R6, R9, 10k, 1% KOA Speer RK73GC1JLTD1002F0603 R14, R18, R20, Electronics Inc., R21, R22, R27, Bradford, PA, USAR28 R7, R10, R12, 100k, 1% KOA Speer RK73GC1JLTD1003F 0603 R13, R15,R19, Electronics Inc., R23, R24 Bradford, PA, USA R2, R4, R8 3.3k, 5%,KOA Speer RK73B2ELTDD332J 1210 500 mW Electronics Inc., Bradford, PA,USA R3, R16, R17 33.2k, 1% KOA Speer RK73GC1JLTD3322F 0603 ElectronicsInc., Bradford, PA, USA U1 8 BIT Motorola Inc. MC68HC908KX8MDW SOIC 16Micro-controller U2 5 V protected Micrel MIC2951-02BM SOIC 8 regulatorSemiconductor, Inc. San Jose, CA, USA

The Appendix is a software listing of the following computer file:Appendix containing file HOTSHOT2.S19 and of length 5,434 bytes. Toprogram the FLASH memory on the Motorola 68HC908 microcontroller thatresides inside the Hotshot product the following steps need to beconducted:

-   1). Provide a Personal Computer, such as an Intel-based Pentium III    800 MHz computer, 256 MB RAM and 2 GB Hard Disk configured with    Microsoft Windows 2000 operating system.-   2). Start the Prog08SZ.exe programmer for Windows version 1.38    provided from P&E Microcomputers System Inc, PO Box 2044, Woburn    Mass. 01888-00044 U.S.A.    -   a). Select>File>load S19 record        -   1). Create the file HOTSHOT2.S19 based on the Appendix and            place it into a temporary directory.    -   b). Select>Program        -   1). The Prog08SZ.exe program will read the HOTSHOT2.S19 file            and translate this information into the FLASH program and            too the threshold parameters.        -   2). The program will indicate when programming is complete.

It is appreciated that the software components of the present inventionmay, if desired, be implemented in ROM (read-only memory) form. Thesoftware components may, generally, be implemented in hardware, ifdesired, using conventional techniques.

It is appreciated that the particular embodiment implemented by theAppendix is intended only to provide an extremely detailed disclosure ofthe present invention and is not intended to be limiting.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove but rather includes both combinations andsubcombinations of the various features described hereinabove as well asmodifications thereto which would occur to a person reading theforegoing which modifications are not in the prior art. 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1-259. (canceled)
 260. Apparatus for spraying a liquid onto at least onevehicle surface comprising: a liquid reservoir; a vehicle surface liquidheating assembly receiving a liquid from said liquid reservoir, saidvehicle surface liquid heating assembly comprising: a heat-conductiveelement; and a liquid heating enclosure defining a liquid heating volumeincluding a primary liquid heating volume portion and a secondary liquidheating volume portion, separated by said heat-conductive element, saidprimary liquid heating volume portion including a heat exchanger fordirectly heating liquid in said primary liquid heating volume portionand for indirectly heating liquid in said secondary liquid heatingvolume portion via said heat-conductive element; a vehicle surfaceliquid spraying assembly receiving heated liquid from said vehiclesurface liquid heating assembly; and a heated liquid spray controlsubassembly employing said vehicle surface liquid heating assembly andsaid vehicle surface liquid spraying assembly for providing a spray ofsaid heated liquid onto said at least one vehicle surface. 261.Apparatus according to claim 260 and wherein said heat-conductiveelement comprises a displaceable, resilient, flexible element. 262.Apparatus according to claim 260 and wherein said heat-conductiveelement forms at least a wall both of said primary liquid heating volumeportion and of said secondary liquid heating volume portion. 263.Apparatus according to claim 260 and wherein at least said liquidheating enclosure defines a primary liquid flow pathway in said primaryliquid heating volume portion and a secondary liquid flow pathway insaid secondary liquid heating volume portion, said secondary liquid flowpathway supplying liquid to said primary liquid flow pathway. 264.Apparatus according to claim 260 and wherein said primary liquid heatingvolume portion is formed of a relatively rigid, highly heat conductivematerial.
 265. Apparatus according to claim 264 and wherein saidsecondary liquid heating volume portion is formed of a material which isless rigid and less heat conductive than said material forming saidprimary liquid heating volume portion.
 266. Apparatus according to claim263 and wherein at least said primary liquid flow pathway is defined bysaid liquid heating enclosure and by said heat-conductive element. 267.Apparatus according to claim 260 and wherein at least said liquidheating enclosure defines an at least partially turbulent flow primaryliquid flow pathway in said primary liquid heating volume portion and anat least partially turbulent flow secondary liquid flow pathway in saidsecondary liquid heating volume portion, said at least partiallyturbulent flow secondary liquid flow pathway supplying liquid to said atleast partially turbulent flow primary liquid flow pathway. 268.Apparatus according to claim 260 and wherein said primary liquid heatingvolume portion is formed at least partially of a metal material, whichis relatively highly heat conductive and said secondary liquid heatingvolume portion is formed at least partially of a plastic material, whichis relatively heat insulative, separated by said heat-conductiveelement, said heat-conductive element being formed of a material whichis less heat conductive than said metal material and more heatconductive than said plastic material.
 269. Apparatus according to claim260 and wherein said heat-conductive element is apertured to permitliquid communication from said secondary liquid heating volume portionto said primary liquid heating volume portion.
 270. Apparatus accordingto claim 260 and wherein said secondary liquid heating volume portionincludes at least one displaceable outer wall portion providing freezeprotection by virtue of its displaceability.
 271. Apparatus according toclaim 270 and wherein said heat-conductive element comprises adisplaceable element operative to be displaced into said secondaryliquid heating volume portion upon freezing of liquid inside saidprimary liquid heating volume portion.
 272. Apparatus according to claim260 and wherein said heat-conductive element is an intervening liquidimpermeable displaceable diaphragm.
 273. Apparatus according to claim260 and wherein said primary liquid heating volume portion is a firstconduit element and said secondary liquid heating volume portion is asecond conduit element.
 274. Apparatus according to claim 273 andwherein said heat exchanger is defined by said first conduit element andsaid second conduit element.
 275. Apparatus according to claim 260 andwherein said at least one vehicle surface includes at least one of thefollowing surfaces: a front vehicle windshield surface, a back vehiclewindshield surface, side vehicle windows, a vehicle headlight surface, avehicle rear light surface, a vehicle radar antenna surface and avehicle exterior mirror surface.
 276. Apparatus according to claim 260and wherein said heated liquid spray control subassembly is operative toemploy said vehicle surface liquid heating assembly and said vehiclesurface liquid spraying assembly for providing a spray of liquid onto avehicle windshield surface and a vehicle radar antenna surface. 277.Apparatus according to claim 276 and also comprising a normally-openvalve interconnecting vehicle windshield sprayers of said vehiclewindshield surface to said vehicle surface liquid spraying assembly andbeing operative, when open, to bypass vehicle radar antenna sprayers ofsaid vehicle radar antenna surface.
 278. Apparatus according to claim277 and also comprising a flow restrictor, restricting liquid flow tosaid vehicle radar antenna sprayers to ensure liquid is supplied to saidvehicle windshield sprayers when said normally-open valve is open. 279.Apparatus for spraying a liquid onto at least one vehicle surfacecomprising: a liquid reservoir; a vehicle surface liquid heatingassembly receiving a liquid from said liquid reservoir; a vehiclesurface liquid spraying assembly receiving heated liquid from saidvehicle surface liquid heating assembly; and a heated liquid spraycontrol subassembly employing said vehicle surface liquid heatingassembly and said vehicle surface liquid spraying assembly for providinga spray of said heated liquid onto said at least one vehicle surface;and a normally closed automatically operative valve interconnecting saidliquid reservoir to said vehicle surface liquid spraying assembly andbeing operative, when open, to bypass said liquid heating assembly. 280.Apparatus according to claim 279 and also comprising a vehicle pumpconnected upstream of said at least one liquid reservoir and downstreamof said normally closed automatically operative valve.
 281. Apparatusaccording to claim 279 and wherein said at least one vehicle surfaceincludes at least one of the following surfaces: a front vehiclewindshield surface, a back vehicle windshield surface, a side vehiclewindow, a vehicle headlight surface, a vehicle rear light surface, avehicle radar antenna surface and a vehicle exterior mirror surface.282. Apparatus according to claim 279 and wherein said normally closedautomatically operative valve is a differential pressure responsiveone-way valve.
 283. Apparatus according to claim 279 and wherein said atleast one vehicle surface includes a first surface and a second surfaceand said apparatus also comprises a normally-open valve interconnectingvehicle sprayers of said first surface to said vehicle surface liquidspraying assembly and being operative, when open, to bypass vehiclesprayers of said second surface.
 284. Apparatus according to claim 283and also comprising a flow restrictor, restricting liquid flow to saidvehicle sprayers of said second surface to ensure liquid is supplied tosaid vehicle sprayers of said first surface when said normally-openvalve is open.
 285. Apparatus according to claim 284 and wherein saidfirst surface is a vehicle windshield surface.
 286. A method forspraying a liquid onto at least one vehicle surface comprising:providing a vehicle including said at least one vehicle surface and aliquid reservoir; supplying said liquid from said liquid reservoir to avehicle surface liquid heating assembly including a primary liquidheating volume portion and a secondary liquid heating volume portion,separated by a heat-conductive element; directly heating said liquid insaid primary liquid heating volume portion, thereby indirectly heatingsaid liquid in said secondary liquid heating volume portion via saidheat-conductive element; and thereafter spraying said liquid onto saidat least one vehicle surface.
 287. A method according to claim 286 andwherein said spraying includes spraying said liquid for an initial spraycycle.
 288. A method according to claim 287 and wherein said indirectlyheating liquid in said secondary liquid heating volume portion during arelatively long time duration after initial operation of a motor of saidvehicle causes said initial spray cycle to be relatively longer thanwhen said indirectly heating liquid in said secondary liquid heatingvolume portion is during a relatively short time duration after saidinitial operation of said motor of said vehicle.
 289. A method accordingto claim 287 and wherein said spraying said liquid onto said at leastone vehicle surface is nearly instantaneous when said indirectly heatingliquid in said secondary liquid heating volume portion is for arelatively short time duration after said initial operation of saidmotor of said vehicle.
 290. A method according to claim 287 and whereinsaid indirectly heating liquid in said secondary liquid heating volumeportion during a relatively long time duration after a previous spraycycle causes said initial spray cycle to be relatively longer than whensaid indirectly heating liquid in said secondary liquid heating volumeportion is during a relatively short time duration after said previousspray cycle.
 291. A method according to claim 287 and wherein saidspraying said liquid onto said at least one vehicle surface is nearlyinstantaneous when said indirectly heating liquid in said secondaryliquid heating volume portion is for a relatively short time durationafter a previous spray cycle.
 292. A heated liquid discharge systemcomprising: a main assembly which provides liquid heating and includeselectrical and liquid flow control functionalities; a liquid inflowconduit supplying liquid from a liquid reservoir to said main assembly;and a liquid outflow conduit supplying liquid to at least one sprayerlocated at at least one location on a motor vehicle, said liquid inflowconduit having connected in series therewith a leaky one-way valve whichpermits limited backflow of liquid from said main assembly to saidreservoir.
 293. A heated liquid discharge system according to claim 292and wherein said main assembly comprises a liquid heating chambercommunicating with said liquid inflow conduit and said liquid outflowconduit and being formed with a liquid drain aperture located on a sidethereof which permits draining of liquid from said liquid heatingchamber generally down to a level of said liquid drain aperture via saidleaky one-way valve.
 294. A heated liquid discharge system according toclaim 293 and wherein said draining takes place when a vehicle pumpsupplying liquid to said liquid inflow conduit is not in operation. 295.A heated liquid discharge system according to claim 292 and wherein saidat least one location includes at least one of the following locations:front vehicle windshield, back vehicle windshield, side vehicle windows,vehicle headlights, vehicle rear lights and vehicle exterior mirrors.296. A heated liquid discharge system according to claim 292 and alsocomprising an overheating cut-off fuse for shutting off electrical powerto at least part of said main assembly in the event of overheating of aliquid heating chamber located within said main assembly.
 297. A heatedliquid discharge system according to claim 296 and wherein said fuse isformed with an undersurface of a resilient material and is retained intight thermal engagement with the underside of a base of a liquidheating element located within said liquid heating chamber.
 298. Aheated liquid discharge system according to claim 293 and wherein saidliquid drain aperture together with said leaky one-way valve providesboth overheating and anti-freezing protection for said main assembly.299. Apparatus for spraying a liquid onto at least one vehicle surfacecomprising: a liquid reservoir; a vehicle surface liquid heatingassembly receiving a liquid from said liquid reservoir; a vehiclesurface liquid spraying assembly receiving heated liquid from saidvehicle surface liquid heating assembly; and a heated liquid spraycontrol subassembly employing said vehicle surface liquid heatingassembly and said vehicle surface liquid spraying assembly for providinga spray of said heated liquid onto said at least one vehicle surface,said spray of said heated liquid being automatically activated by anautomatic gain control circuit (AGC) actuation signal.